ULTRAMAR CORP /DE
8-K, 1996-09-25
PETROLEUM REFINING
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                SECURITIES AND EXCHANGE COMMISSION
                      Washington, D.C. 20549


                             Form 8-K
                          CURRENT REPORT


      Pursuant to Section 13 or 15(d) of the Securities and
                      Exchange Act of 1934


        Date of Report (Date of earliest event reported)
                       September 22, 1996



                       ULTRAMAR CORPORATION
- ---------------------------------------------------------------------
      (Exact name of registrant as specified in its charter)



   Delaware               1-11154                   13-3663331
 -----------            -----------             -------------------
  (State of             (Commission                (IRS Employer
incorporation           File Number             Indentification No.



Two Pickwick Plaza, Greenwich, Connecticut          06830
- ------------------------------------------        ----------
 (Address of principal executive offices)         (Zip Code)



Registrant's telephone number, including area code (203) 622-7000


<PAGE>


Item 5.  Other Events.

      On September 22, 1996, Ultramar Corporation ("UC") entered
into an Agreement and Plan of Merger (the "Merger Agreement")
with Diamond Shamrock, Inc. ("DSI"). Pursuant to the Merger
Agreement, DSI will be merged with and into UC. In connection
with the Merger Agreement, DSI granted UC an option to purchase
up to 19.9% of the common stock of DSI pursuant to a Stock Option
Agreement (the "DSI Stock Option Agreement") dated as of
September 22, 1996. The option becomes exercisable upon the
occurrence of certain events, none of which has occurred at the
time of this filing. Also in connection with the Merger
Agreement, UC granted DSI an option to purchase up to 19.9% of
the common stock of UC, on terms substantially similar to those
contained in the DSI Stock Option Agreement, pursuant to a Stock
Option Agreement (the "UC Stock Option Agreement") dated as of
September 22, 1996. In addition, UC entered into an amendment
dated as of September 22, 1996, (the "Rights Agreement
Amendment") to its Right Agreement dated as of June 25, 1992, as
amended by the First Amendment dated as of October 26, 1992, and
the Amendment dated as of May 10, 1994 (as amended, the "Rights
Agreement"), for the purpose of excluding DSI and any of its
wholly-owned subsidiaries from the definition of Acquiring Person
solely as a result of DSI's execution and delivery of the Merger
Agreement or the UC Stock Option Agreement or the consummation of
the transactions contemplated by the Merger Agreement or the UC
Stock Option Agreement. Copies of the Merger Agreement, Rights
Agreement Amendment, Rights Agreement, DSI Stock Option
Agreement, UC Stock Option Agreement and press release announcing
execution of the Merger Agreement are attached hereto as Exhibits
2.1, 4.1, 4.2, 10.1, 10.2 and 99.1, respectively, and by this
reference made a part hereof.

Item 7.  Financial Statements, Pro Forma Financial Information
         and Exhibits.

       1.  Financial Statements of Business Acquired. Not Applicable.

       2.  Pro Forma Financial Information. Not Applicable.

       3.  Exhibits. See the Index to Exhibits attached hereto.

                              Page 2

<PAGE>


                            SIGNATURES

      Pursuant to the requirements of the Securities Exchange Act
of 1934, the Registrant has duly caused this report to be signed
on its behalf by the undersigned hereunto duly authorized.



                                   ULTRAMAR CORPORATION
                                   -----------------------
                                       (Registrant)

Dated:  September 25, 1996

                                   By: /s/ H. Pete Smith
                                      --------------------------------
                                      Name:  H. Pete Smith 
                                      Title: Senior Vice President and
                                             Chief Financial Officer


                                           Page 3

<PAGE>


                          EXHIBIT INDEX




      Exhibit        Description                                 Page

        2.1          Agreement and Plan of Merger between
                     Ultramar Corporation and Diamond
                     Shamrock, Inc. dated as of
                     September 22, 1996.

        4.1          Amendment dated as of September 22,
                     1996, to the Rights Agreement dated
                     as of June 25, 1992 between Ultramar
                     Corporation and Registrar and
                     Transfer Company (as successor rights
                     agent to First City, Texas-Houston,
                     National Association), as amended by
                     the First Amendment dated as of
                     October 26, 1992 and the Amendment
                     dated as of May 10, 1994.

        4.2          Rights Agreement dated as of June 25,
                     1992 between Ultramar Corporation and
                     Registrar and Transfer Company (as
                     successor rights agent to First City,
                     Texas-Houston, National Association),
                     as amended by the First Amendment
                     dated as of October 26, 1992, and the
                     Amendment dated as of May 10, 1994
                     (incorporated by reference to
                     Registration Statement on Form S-1
                     (File No. 33-47586), Exhibit 4.2;
                     Quarterly Report on Form 10-Q for the
                     Quarter Ended September 30, 1992,
                     Exhibit 4.2; Annual Report on Form
                     10-K for the Year Ended December 31,
                     1994, Exhibit 4.3).

        10.1         Stock Option Agreement dated as of
                     September 22, 1996 between Diamond
                     Shamrock, Inc., as Issuer, and
                     Ultramar Corporation, as Grantee.

        10.2         Stock Option Agreement dated as of
                     September 22, 1996 between Ultramar
                     Corporation, as Issuer, and Diamond
                     Shamrock, Inc., as Grantee.

        99.1         Press Release dated September 23,
                     1996.



                              Page 4



                                                   Exhibit 2.1


==============================================================
                 AGREEMENT AND PLAN OF MERGER


                            between



                     ULTRAMAR CORPORATION



                              and



                    DIAMOND SHAMROCK, INC.







                Dated as of September 22, 1996




==============================================================


<PAGE>


                       TABLE OF CONTENTS


                                                          Page

                           ARTICLE I

                          The Merger

SECTION 1.01.  The Merger.................................   2
SECTION 1.02.  Closing....................................   2
SECTION 1.03.  Effective Time.............................   3
SECTION 1.04.  Effects of the Merger......................   3
SECTION 1.05.  Certificate of Incorporation and By-laws...   3
SECTION 1.06.  Boards, Committees and Officers............   3


                          ARTICLE II

                  Effect of the Merger on the
               Capital Stock of the Constituent
            Corporations; Exchange of Certificates

SECTION 2.01.  Effect on Capital Stock....................   4
SECTION 2.02.  Exchange of Certificates...................   5


                          ARTICLE III

                Representations and Warranties

SECTION 3.01.  Representations and Warranties of DSI......  12
SECTION 3.02.  Representations and Warranties of UC.......  25


                          ARTICLE IV

           Covenants Relating to Conduct of Business

SECTION 4.01.  Conduct of Business........................  36
SECTION 4.02.  No Solicitation by DSI.....................  44
SECTION 4.03.  No Solicitation by UC......................  46


<PAGE>


                                                          Page

                           ARTICLE V

                     Additional Agreements

SECTION 5.01.  Preparation of the Form S-4 and the Joint 
                Proxy Statement; Stockholders Meetings....  49
SECTION 5.02.  Letters of DSI's Accountants...............  51
SECTION 5.03.  Letters of UC's Accountants................  51
SECTION 5.04.  Access to Information; Confidentiality.....  51
SECTION 5.05.  Reasonable Efforts.........................  52
SECTION 5.06.  Stock Options..............................  53
SECTION 5.07.  Certain Employee Matters ..................  55
SECTION 5.08.  Indemnification, Exculpation and
                Insurance.................................  55
SECTION 5.09.  Fees and Expenses..........................  56
SECTION 5.10.  Public Announcements.......................  58
SECTION 5.11.  Affiliates.................................  58
SECTION 5.12.  NYSE Listing...............................  59
SECTION 5.13.  Stockholder Litigation.....................  59
SECTION 5.14.  Tax Treatment..............................  59
SECTION 5.15.  Pooling of Interests.......................  59
SECTION 5.16.  DSI Rights Agreement.......................  60
SECTION 5.17.  UC Rights Agreement........................  60
SECTION 5.18.  Headquarters...............................  60
SECTION 5.19.  UC Convertible Preferred Stock.............  60
SECTION 5.20.  Indemnification Agreements.................  61
SECTION 5.21.  Certain Tax Matters........................  61


                          ARTICLE VI

                     Conditions Precedent

SECTION 6.01.  Conditions to Each Party's Obligation to
                Effect the Merger.........................  61
SECTION 6.02.  Conditions to Obligations of UC............  63
SECTION 6.03.  Conditions to Obligation of DSI............  64
SECTION 6.04.  Frustration of Closing Conditions..........  65


                          ARTICLE VII

               Termination, Amendment and Waiver

SECTION 7.01.  Termination................................  65
SECTION 7.02.  Effect of Termination......................  68


<PAGE>


                                                          Page

SECTION 7.03.  Amendment..................................  68
SECTION 7.04.  Extension; Waiver..........................  68
SECTION 7.05.  Procedure for Termination, Amendment,
                Extension or Waiver.......................  68


                         ARTICLE VIII

                      General Provisions

SECTION 8.01.  Nonsurvival of Representations and
                Warranties................................  69
SECTION 8.02.  Notices....................................  69
SECTION 8.03.  Definitions................................  70
SECTION 8.04.  Interpretation.............................  71
SECTION 8.05.  Counterparts...............................  71
SECTION 8.06.  Entire Agreement; No Third Party
                Beneficiaries.............................  72
SECTION 8.07.  Governing Law..............................  72
SECTION 8.08.  Assignment.................................  72
SECTION 8.09.  Enforcement................................  72


Exhibit A      Amendments to Certificate of Incorporation
                and By-laws
Exhibit B      Board, Committees and Officers
Exhibit C      Affiliate Letter
Exhibit D      UC Tax Representations
Exhibit E      DSI Tax Representations
Exhibit F      DSI Stockholder Tax Representations

Schedule 5.07  Certain Employee Matters


<PAGE>


                    AGREEMENT AND PLAN OF MERGER dated as of
               September 22, 1996, between ULTRAMAR
               CORPORATION, a Delaware corporation ("UC"),
               and DIAMOND SHAMROCK, INC., a Delaware
               corporation ("DSI").


          WHEREAS, the respective Boards of Directors of UC
and DSI have approved the merger of DSI with and into UC
(the "Merger"), upon the terms and subject to the conditions
set forth in this Agreement, whereby (a) each issued and
outstanding share of common stock, par value $.01 per share,
of DSI ("DSI Common Stock"), other than shares owned by UC,
DSI or any of their wholly owned subsidiaries, will be
converted into the right to receive the Merger Consideration
(as defined in Section 2.01(b)) and (b) each issued and
outstanding share of 5% Cumulative Convertible Preferred
Stock, par value $.01 per share, of DSI (the "DSI
Convertible Preferred Stock"), other than shares owned by
UC, DSI or any of their wholly owned subsidiaries, will be
converted into the right to receive one share of 5%
Cumulative Convertible Preferred Stock, par value $.01 per
share, of UC (the "UC Convertible Preferred Stock");

          WHEREAS, the respective Boards of Directors of UC
and DSI have each determined that the Merger and the other
transactions contemplated hereby are consistent with, and in
furtherance of, their respective business strategies and
goals;

          WHEREAS, UC and DSI desire to make certain
representations, warranties, covenants and agreements in
connection with the Merger and also to prescribe various
conditions to the Merger;

          WHEREAS, for federal income tax purposes, it is
intended that the Merger will qualify as a reorganization
under the provisions of Section 368(a) of the Internal
Revenue Code of 1986, as amended (the "Code");

          WHEREAS, for financial accounting purposes, it is
intended that the Merger will be accounted for as a pooling
of interests transaction;

          WHEREAS, immediately following the execution and
delivery of this Agreement, DSI and UC will enter into a
stock option agreement (the "DSI Stock Option Agreement"),
pursuant to which DSI will grant UC the option (the "DSI


<PAGE>


Option") to purchase shares of DSI Common Stock together
with the associated DSI Rights (as defined in Section
3.01(c)) upon the terms and subject to the conditions set
forth therein; and

          WHEREAS, immediately following the execution and
delivery of this Agreement, UC and DSI will enter into a
stock option agreement (the "UC Stock Option Agreement",
and, together with the DSI Stock Option Agreement, the
"Option Agreements"), pursuant to which UC will grant DSI
the option (the "UC Option") to purchase shares of common
stock, par value $.01 per share, of UC ("UC Common Stock")
together with the associated UC Rights (as defined in
Section 3.02(c)) upon the terms and subject to the
conditions set forth therein.


          NOW, THEREFORE, in consideration of the
representations, warranties, covenants and agreements
contained in this Agreement, the parties agree as follows:


                          ARTICLE I

                         The Merger

          SECTION 1.01. The Merger. Upon the terms and
subject to the conditions set forth in this Agreement, and
in accordance with the Delaware General Corporation Law (the
"DGCL"), DSI shall be merged with and into UC at the
Effective Time (as defined in Section 1.03). Following the
Effective Time, UC shall be the surviving corporation (the
"Surviving Corporation") and shall succeed to and assume all
the rights and obligations of DSI in accordance with the
DGCL.

          SECTION 1.02. Closing. The closing of the Merger
(the "Closing") will take place at 10:00 a.m. on a date to
be specified by the parties (the "Closing Date"), which
(subject to satisfaction or waiver of the conditions set
forth in Sections 6.01, 6.02 and 6.03) shall be no later
than the second business day after satisfaction or waiver of
the conditions set forth in Section 6.01, unless another
time or date is agreed to by the parties hereto. The Closing
will be held at such location in the City of New York as is
agreed to by the parties hereto.


<PAGE>


          SECTION 1.03. Effective Time. Subject to the
provisions of this Agreement, as soon as practicable on or
after the Closing Date, the parties shall file a certificate
of merger or other appropriate documents (in any such case,
the "Certificate of Merger") executed in accordance with the
relevant provisions of the DGCL and shall make all other
filings or recordings required under the DGCL. The Merger
shall become effective at such time as the Certificate of
Merger is duly filed with the Delaware Secretary of State,
or at such subsequent date or time as UC and DSI shall agree
and specify in the Certificate of Merger (the time the
Merger becomes effective being hereinafter referred to as
the "Effective Time").

          SECTION 1.04. Effects of the Merger. The Merger
shall have the effects set forth in Section 259 of the DGCL.

          SECTION 1.05. Certificate of Incorporation and
By-laws. (a) The certificate of incorporation of UC, as in
effect immediately prior to the execution of this Agreement,
shall be amended as of the Effective Time as set forth in
Exhibit A and, as so amended, such certificate of
incorporation shall be the certificate of incorporation of
the Surviving Corporation until thereafter changed or
amended as provided therein or by applicable law.

          (b) The by-laws of UC, as in effect immediately
prior to the execution of this Agreement, shall be amended
as of the Effective Time as set forth in Exhibit A and, as
so amended, such by-laws shall be the by-laws of the
Surviving Corporation until thereafter changed or amended as
provided therein or by applicable law.

          SECTION 1.06.  Boards, Committees and Officers. 
The Board of Directors (including classes thereof),
committees of the Board of Directors, composition of such
committees (including chairmen thereof) and officers of the
Surviving Corporation shall be as set forth on Exhibit B
hereto until the earlier of the resignation or removal of
any individual listed on or designated in accordance with
Exhibit B or until their respective successors are duly
elected and qualified, as the case may be, it being agreed
that if any director shall be unable to serve as a director
(including as a member or chairman of any committee) at the
Effective Time the party which designated such individual as
indicated in Exhibit B shall designate another individual to
serve in such individual's place. If any officer listed on
or appointed in accordance with Exhibit B ceases to be a


<PAGE>


full-time employee of either DSI or UC, the parties will
agree upon another person to serve in such person's stead.
The committees of the Board of Directors of UC will have
such authority as may, subject to applicable law, be
delegated to them by the Board of Directors.


                         ARTICLE II

      Effect of the Merger on the Capital Stock of the
     Constituent Corporations; Exchange of Certificates

          SECTION 2.01. Effect on Capital Stock. As of the
Effective Time, by virtue of the Merger and without any
action on the part of the holder of any shares of DSI Common
Stock, DSI Convertible Preferred Stock or UC Common Stock:

          (a) Cancelation of Treasury Stock and UC-Owned
     Stock. Each share of DSI Common Stock and DSI
     Convertible Preferred Stock that is owned by DSI or by
     any wholly owned subsidiary of DSI or by UC or any
     wholly owned subsidiary of UC shall automatically be
     canceled and retired and shall cease to exist, and no
     consideration shall be delivered in exchange therefor.

          (b) Conversion of DSI Common Stock. Subject to
     Section 2.02(e), each issued and outstanding share of
     DSI Common Stock (other than shares to be canceled in
     accordance with Section 2.01(a)) shall be converted
     into the right to receive 1.02 fully paid and
     nonassessable shares of UC Common Stock (the "Merger
     Consideration"). As of the Effective Time, all such
     shares of DSI Common Stock shall no longer be
     outstanding and shall automatically be canceled and
     retired and shall cease to exist, and each holder of a
     certificate representing any such shares of DSI Common
     Stock shall cease to have any rights with respect
     thereto, except the right to receive the Merger
     Consideration and any cash in lieu of fractional shares
     of UC Common Stock to be issued or paid in
     consideration therefor upon surrender of such
     certificate in accordance with Section 2.02, without
     interest.

          (c)  Conversion of DSI Convertible Preferred 
     Stock. Each issued and outstanding share of DSI
     Convertible Preferred Stock (other than shares to be
     canceled in accordance with Section 2.01(a) and shares


<PAGE>


     held by persons who perfect their appraisal rights
     under the DGCL) shall be converted into the right to
     receive one fully paid and nonassessable share of UC
     Convertible Preferred Stock, which UC Convertible
     Preferred Stock (i) will have terms that are identical
     to the DSI Convertible Preferred Stock (as a result of
     the Merger, (x) the issuer thereof will be UC rather
     than DSI and (y) in accordance with the terms of the
     DSI Preferred Stock, the UC Convertible Preferred Stock
     will be convertible as of the Effective Time at the
     conversion price necessary to make each share of UC
     Convertible Preferred Stock convertible into the number
     of shares of UC Common Stock receivable upon the Merger
     by a holder of the number of shares of DSI Common Stock
     into which one share of DSI Convertible Preferred Stock
     might have been converted immediately prior to the
     Merger), and (ii) will be issued pursuant to action
     taken by the Board of Directors of UC. As of the
     Effective Time, all such shares of DSI Convertible
     Preferred Stock shall no longer be outstanding and
     shall automatically be canceled and retired and shall
     cease to exist, and each holder of a certificate
     representing any such shares of DSI Convertible
     Preferred Stock shall cease to have any rights with
     respect thereto, except the right to receive one share
     of UC Convertible Preferred Stock to be issued in
     consideration therefor upon surrender of such
     certificate in accordance with Section 2.02, without
     interest.

          SECTION 2.02. Exchange of Certificates.
(a)  Exchange Agent. As of the Effective Time, UC shall
enter into an agreement with such bank or trust company as
may be designated by UC and DSI (the "Exchange Agent"),
which shall provide that UC shall deposit with the Exchange
Agent as of the Effective Time, for the benefit of the
holders of shares of DSI Common Stock and DSI Convertible
Preferred Stock, for exchange in accordance with this
Article II, through the Exchange Agent, certificates
representing the shares of UC Common Stock and UC
Convertible Preferred Stock (such shares of UC Common Stock
and UC Convertible Preferred Stock, together with any
dividends or distributions with respect thereto with a
record date after the Effective Time, any Excess Shares (as
defined in Section 2.02(e)) and any cash (including cash
proceeds from the sale of the Excess Shares) payable in lieu
of any fractional shares of UC Common Stock being
hereinafter referred to as the "Exchange Fund") issuable


<PAGE>


pursuant to Section 2.01 in exchange for outstanding shares
of DSI Common Stock and DSI Convertible Preferred Stock.

          (b) Exchange Procedures. As soon as reasonably
practicable after the Effective Time, the Exchange Agent
shall mail to each holder of record of a certificate or
certificates which immediately prior to the Effective Time
represented outstanding shares of DSI Common Stock or DSI
Convertible Preferred Stock (the "Certificates") whose
shares were converted into the right to receive the Merger
Consideration or shares of UC Convertible Preferred Stock,
as applicable, pursuant to Section 2.01, (i) a letter of
transmittal (which shall specify that delivery shall be
effected, and risk of loss and title to the Certificates
shall pass, only upon delivery of the Certificates to the
Exchange Agent and shall be in such form and have such other
provisions as UC and DSI may reasonably specify) and
(ii) instructions for use in effecting the surrender of the
Certificates in exchange for the Merger Consideration or
shares of UC Convertible Preferred Stock, as applicable.
Upon surrender of a Certificate for cancelation to the
Exchange Agent or to such other agent or agents as may be
appointed by UC, together with such letter of transmittal,
duly executed, and such other documents as may reasonably be
required by the Exchange Agent, the holder of such
Certificate shall be entitled to receive in exchange
therefor a certificate representing that number of whole
shares of UC Common Stock or UC Convertible Preferred Stock
and, in the case of Certificates representing DSI Common
Stock, cash, if any, which such holder has the right to
receive pursuant to the provisions of this Article II, and
the Certificate so surrendered shall forthwith be canceled.
In the event of a transfer of ownership of DSI Common Stock
or DSI Convertible Preferred Stock which is not registered
in the transfer records of DSI, a certificate representing
the proper number of shares of UC Common Stock or UC
Convertible Preferred Stock may be issued to a person other
than the person in whose name the Certificate so surrendered
is registered if such Certificate shall be properly endorsed
or otherwise be in proper form for transfer and the person
requesting such issuance shall pay any transfer or other
taxes required by reason of the issuance of shares of UC
Common Stock or UC Convertible Preferred Stock to a person
other than the registered holder of such Certificate or
establish to the satisfaction of UC that such tax has been
paid or is not applicable. Until surrendered as 
contemplated by this Section 2.02, each Certificate shall be
deemed at any time after the Effective Time to represent


<PAGE>


only the right to receive upon such surrender the Merger
Consideration or shares of UC Convertible Preferred Stock,
as applicable, and, in the case of Certificates representing
DSI Common Stock, cash, if any, which the holder thereof has
the right to receive in respect of such Certificate pursuant
to the provisions of this Article II. No interest will be
paid or will accrue on any cash payable to holders of
Certificates pursuant to the provisions of this Article II.

          (c) Distributions with Respect to Unexchanged
Shares. No dividends or other distributions with respect to
UC Common Stock or UC Convertible Preferred Stock with a
record date after the Effective Time shall be paid to the
holder of any unsurrendered Certificate with respect to the
shares of UC Common Stock or UC Convertible Preferred Stock
represented thereby, and, in the case of Certificates
representing DSI Common Stock, no cash payment in lieu of
fractional shares shall be paid to any such holder pursuant
to Section 2.02(e), and all such dividends, other
distributions and cash in lieu of fractional shares of UC
Common Stock shall be paid by UC to the Exchange Agent and
shall be included in the Exchange Fund, in each case until
the surrender of such Certificate in accordance with this
Article II. Subject to the effect of applicable escheat or
similar laws, following surrender of any such Certificate
there shall be paid to the holder of the certificate
representing whole shares of UC Common Stock or UC
Convertible Preferred Stock issued in exchange therefor,
without interest, (i) at the time of such surrender, the
amount of dividends or other distributions with a record
date after the Effective Time theretofore paid with respect
to such whole shares of UC Common Stock or UC Convertible
Preferred Stock, and, in the case of Certificates
representing DSI Common Stock, the amount of any cash
payable in lieu of a fractional share of UC Common Stock to
which such holder is entitled pursuant to Section 2.02(e)
and (ii) at the appropriate payment date, the amount of
dividends or other distributions with a record date after
the Effective Time but prior to such surrender and with a
payment date subsequent to such surrender payable with
respect to such whole shares of UC Common Stock or UC
Convertible Preferred Stock.

          (d) No Further Ownership Rights in DSI Common
Stock or DSI Convertible Preferred Stock. All shares of UC
Common Stock or UC Convertible Preferred Stock issued upon
the surrender for exchange of Certificates in accordance
with the terms of this Article II (including any cash paid


<PAGE>


pursuant to this Article II) shall be deemed to have been
issued (and paid) in full satisfaction of all rights
pertaining to the shares of DSI Common Stock or DSI
Convertible Preferred Stock, as applicable, theretofore
represented by such Certificates, subject, however, to the
Surviving Corporation's obligation to pay any dividends or
make any other distributions with a record date prior to the
Effective Time which may have been declared or made by DSI
on such shares of DSI Common Stock or DSI Convertible
Preferred Stock which remain unpaid at the Effective Time,
and there shall be no further registration of transfers on
the stock transfer books of the Surviving Corporation of the
shares of DSI Common Stock or DSI Convertible Preferred
Stock which were outstanding immediately prior to the
Effective Time. If, after the Effective Time, Certificates
are presented to the Surviving Corporation or the Exchange
Agent for any reason, they shall be canceled and exchanged
as provided in this Article II, except as otherwise provided
by law.

          (e) No Fractional Shares. (i) No certificates or
scrip representing fractional shares of UC Common Stock
shall be issued upon the surrender for exchange of
Certificates, no dividend or distribution of UC shall relate
to such fractional share interests and such fractional share
interests will not entitle the owner thereof to vote or to
any rights of a stockholder of UC.

          (ii) As promptly as practicable following the
Effective Time, the Exchange Agent will determine the excess
of (A) the number of whole shares of UC Common Stock
delivered to the Exchange Agent by UC pursuant to Section
2.02(a) over (B) the aggregate number of whole shares of UC
Common Stock to be distributed to holders of DSI Common
Stock pursuant to Section 2.02(b) (such excess being herein
called the "Excess Shares"). Following the Effective Time,
the Exchange Agent will sell the Excess Shares at
then-prevailing prices on the New York Stock Exchange, Inc.
(the "NYSE"), all in the manner provided in Section
2.02(e)(iii).

          (iii) The sale of the Excess Shares by the
Exchange Agent will be executed on the NYSE through one or
more member firms of the NYSE and will be executed in round
lots to the extent practicable. The Exchange Agent will use
reasonable efforts to complete the sale of the Excess Shares
as promptly following the Effective Time as, in the Exchange
Agent's sole judgment, is practicable consistent with


<PAGE>


obtaining the best execution of such sales in light of
prevailing market conditions. Until the net proceeds of such
sale or sales have been distributed to the holders of DSI
Common Stock, the Exchange Agent will hold such proceeds in
trust for the holders of DSI Common Stock (the "Common
Shares Trust"). The Surviving Corporation will pay all
commissions, transfer taxes and other out-of-pocket
transaction costs, including the expenses and compensation
of the Exchange Agent incurred in connection with such sale
of the Excess Shares. The Exchange Agent will determine the
portion of the Common Shares Trust to which each holder of
DSI Common Stock is entitled, if any, by multiplying the
amount of the aggregate net proceeds comprising the Common
Shares Trust by a fraction, the numerator of which is the
amount of the fractional share interest to which such holder
of DSI Common Stock is entitled (after taking into account
all shares of DSI Common Stock held at the Effective Time by
such holder) and the denominator of which is the aggregate
amount of fractional share interests to which all holders of
DSI Common Stock are entitled.

          (iv) Notwithstanding the provisions of Section
2.02(e)(ii) and (iii), the Surviving Corporation may elect
at its option, exercised prior to the Effective Time, in
lieu of the issuance and sale of Excess Shares and the
making of the payments hereinabove contemplated, to pay each
holder of DSI Common Stock an amount in cash equal to the
product obtained by multiplying (A) the fractional share
interest to which such holder (after taking into account all
shares of DSI Common Stock held at the Effective Time by
such holder) would otherwise be entitled by (B) the closing
price for a share of UC Common Stock as reported on the NYSE
Composite Transaction Tape (as reported in the Wall Street
Journal, or, if not reported thereby, any other
authoritative source) on the Closing Date, and, in such
case, all references herein to the cash proceeds of the sale
of the Excess Shares and similar references will be deemed
to mean and refer to the payments calculated as set forth in
this Section 2.02(e)(iv).

          (v) As soon as practicable after the determination
of the amount of cash, if any, to be paid to holders of DSI
Common Stock with respect to any fractional share interests,
the Exchange Agent will make available such amounts to such
holders of DSI Common Stock subject to and in accordance
with the terms of Section 2.02(c).


<PAGE>


          (f) Termination of Exchange Fund. Any portion of
the Exchange Fund which remains undistributed to the holders
of the Certificates for six months after the Effective Time
shall be delivered to UC, upon demand, and any holders of
the Certificates who have not theretofore complied with this
Article II shall thereafter look only to UC for payment of
their claim for Merger Consideration or shares of UC
Convertible Preferred Stock, any cash in lieu of fractional
shares of UC Common Stock and any dividends or distributions
with respect to UC Common Stock or UC Convertible Preferred
Stock.

          (g) No Liability. None of UC, DSI or the Exchange
Agent shall be liable to any person in respect of any shares
of UC Common Stock or UC Convertible Preferred Stock (or
dividends or distributions with respect thereto) or cash
from the Exchange Fund delivered to a public official
pursuant to any applicable abandoned property, escheat or
similar law. If any Certificate shall not have been
surrendered prior to seven years after the Effective Time
(or immediately prior to such earlier date on which any
Merger Consideration or shares of UC Convertible Preferred
Stock, any cash payable to the holder of such Certificate
representing DSI Common Stock pursuant to this Article II or
any dividends or distributions payable to the holder of such
Certificate would otherwise escheat to or become the
property of any Governmental Entity (as defined in Section
3.01(d)), any such Merger Consideration or shares of UC
Convertible Preferred Stock or cash, dividends or
distributions in respect of such Certificate shall, to the
extent permitted by applicable law, become the property of
the Surviving Corporation, free and clear of all claims or
interest of any person previously entitled thereto.

          (h) Investment of Exchange Fund. The Exchange
Agent shall invest any cash included in the Exchange Fund,
as directed by UC, on a daily basis. Any interest and other
income resulting from such investments shall be paid to UC.

          (i) Lost Certificates. If any Certificate shall
have been lost, stolen or destroyed, upon the making of an
affidavit of that fact by the person claiming such
Certificate to be lost, stolen or destroyed and, if required
by the Surviving Corporation, the posting by such person of
a bond in such reasonable amount as the Surviving
Corporation may direct as indemnity against any claim that
may be made against it with respect to such Certificate, the
Exchange Agent will issue in exchange for such lost, stolen


<PAGE>


or destroyed Certificate the Merger Consideration or shares
of UC Convertible Preferred Stock and, if applicable, any
cash in lieu of fractional shares, and unpaid dividends and
distributions on shares of UC Common Stock or UC Convertible
Preferred Stock deliverable in respect thereof, pursuant to
this Agreement.

          (j) Dissenting Shares. Notwithstanding anything in
this Agreement to the contrary, no share of DSI Convertible
Preferred Stock, the holder of which shall have properly
complied with the provisions of Section 262 of the DGCL as
to appraisal rights (a "Dissenting Share"), will be deemed
to be converted into and to represent the right to receive
one share of UC Convertible Preferred Stock hereunder and
the holders of Dissenting Shares, if any, will be entitled
to payment, solely from the Surviving Corporation, of the
appraised value of such Dissenting Shares to the extent
permitted by and in accordance with the provisions of
Section 262 of the DGCL; provided, however, that (i) if any
holder of Dissenting Shares, under the circumstances
permitted by the DGCL, subsequently delivers a written
withdrawal of his or her demand for appraisal of such
Dissenting Shares, (ii) if any holder fails to establish his
or her entitlement to rights to payment as provided in such
Section 262, or (iii) if neither any holder of Dissenting
Shares nor the Surviving Corporation has filed a petition
demanding a determination of the value of all Dissenting
Shares within the time provided in such Section 262, such
holder will forfeit such right to payment for such
Dissenting Shares pursuant to such Section 262 and, as of
the later of Effective Time or the occurrence of such event,
such holder's Certificate formerly representing shares of
DSI Convertible Preferred Stock shall automatically be
converted into and represent only the right to receive
shares of UC Convertible Preferred Stock pursuant to Section
2.01 hereof, without any interest thereon, upon surrender of
the Certificate or Certificates formerly representing such
shares of DSI Convertible Preferred Stock. DSI shall give UC
(A) prompt notice of any written demands for appraisal of
any Dissenting Shares, attempted withdrawals of such demands
and any other instruments received by DSI relating to
stockholders' rights of appraisal and (B) the opportunity to
participate in all negotiations and proceedings with respect
to demands for appraisal under the DGCL.


<PAGE>


                         ARTICLE III

               Representations and Warranties

          SECTION 3.01. Representations and Warranties of
DSI. Except as disclosed in the DSI Filed SEC Documents (as
such term is defined in Section 3.01(g)) or as set forth on
the Disclosure Schedule delivered by DSI to UC prior to the
execution of this Agreement (the "DSI Disclosure Schedule"),
DSI represents and warrants to UC as follows:

          (a) Organization, Standing and Corporate Power.
     Each of DSI and its Significant Subsidiaries is a
     corporation or other legal entity duly organized,
     validly existing and in good standing (with respect to
     jurisdictions which recognize such concept) under the
     laws of the jurisdiction in which it is organized and
     has the requisite corporate or other power, as the case
     may be, and authority to carry on its business as now
     being conducted. Each of DSI and its Significant
     Subsidiaries is duly qualified or licensed to do
     business and is in good standing (with respect to
     jurisdictions which recognize such concept) in each
     jurisdiction in which the nature of its business or the
     ownership or leasing of its properties makes such
     qualification or licensing necessary, other than in
     such jurisdictions where the failure to be so qualified
     or licensed or to be in good standing individually or
     in the aggregate would not have a material adverse
     effect (as defined in Section 8.03) on DSI. DSI has
     delivered to UC prior to the execution of this
     Agreement complete and correct copies of its
     certificate of incorporation and by-laws and has made
     available to UC the certificates of incorporation and
     by-laws (or comparable organizational documents) of its
     Significant Subsidiaries, in each case as amended to
     date. As used in this Agreement, a "Significant
     Subsidiary" means any subsidiary of DSI or UC, as the
     case may be, that would constitute a "significant
     subsidiary" of such party within the meaning of Rule
     1-02 of Regulation S-X of the Securities and Exchange
     Commission (the "SEC").

          (b) Subsidiaries. Exhibit 21.1 to DSI's Annual
     Report on Form 10-K for the fiscal year ended December
     31, 1995 includes all the subsidiaries of DSI which as
     of the date of this Agreement are Significant
     Subsidiaries. All the outstanding shares of capital


<PAGE>


     stock of, or other equity interests in, each such
     Significant Subsidiary have been validly issued and are
     fully paid and nonassessable and are owned directly or
     indirectly by DSI, free and clear of all pledges,
     claims, liens, charges, encumbrances and security
     interests of any kind or nature whatsoever
     (collectively, "Liens").

          (c) Capital Structure. The authorized capital
     stock of DSI consists of 75,000,000 shares of DSI
     Common Stock and 25,000,000 shares of preferred stock,
     par value $.01 per share, of DSI ("DSI Preferred
     Stock"). At the close of business on September 19,
     1996, (i) 29,292,663 shares of DSI Common Stock were
     issued and outstanding, (ii) 8,079 shares of DSI Common
     Stock were held by DSI in its treasury, (iii) not more
     than 1,725,000 shares of DSI Convertible Preferred
     Stock were issued and outstanding, (iv) no shares of
     DSI Preferred Stock were held by DSI in its treasury,
     (v) 1,672,584 shares of DSI Common Stock were reserved
     for issuance pursuant to the Diamond Shamrock, Inc.
     Long-Term Incentive Plan, the Diamond Shamrock R & M,
     Inc. 1987 Long-Term Incentive Plan, the Diamond
     Shamrock, Inc. Performance Incentive Plan, the 1994
     Restatement of the Diamond Shamrock, Inc. Employee
     Stock Ownership Plan I and the 1994 Restatement of the
     Diamond Shamrock, Inc. Employee Stock Ownership Plan II
     (such plans, collectively, the "DSI Stock Plans"), 
     (vi) not more than 3,254,716 shares of DSI Common Stock
     were reserved for issuance upon conversion of the DSI
     Convertible Preferred Stock, (vii) no shares of Series
     A Junior Participating Preferred Stock (the "Junior
     Preferred Stock") of DSI were issued and outstanding,
     and (viii) other than the DSI Convertible Preferred
     Stock, the Junior Preferred Stock and the $2.00
     Convertible Exchangeable Preferred Stock of DSI (of
     which no shares remain outstanding)(the "DSI $2.00
     Preferred Stock"), no other shares of DSI Preferred
     Stock have been designated or issued. Except as set
     forth above and except for 5,858,500 shares of DSI
     Common Stock (with the associated DSI Rights) reserved
     for issuance upon the exercise of the DSI Option, at
     the close of business on September 19, 1996, no shares
     of capital stock or other voting securities of DSI were
     issued, reserved for issuance or outstanding. At the
     close of business on September 19, 1996 there were no
     outstanding stock appreciation rights or rights (other
     than employee stock options or other rights ("DSI


<PAGE>


     Employee Stock Options", which term shall not include
     performance units granted under the Diamond Shamrock,
     Inc. Long-Term Incentive Plan) to purchase or receive
     DSI Common Stock granted under the DSI Stock Plans) to
     receive shares of DSI Common Stock on a deferred basis
     granted under the DSI Stock Plans or otherwise. The DSI
     Disclosure Schedule sets forth a complete and correct
     list, as of September 19, 1996, of the number of shares
     of DSI Common Stock subject to Employee Stock Options
     and the exercise prices thereof. All outstanding shares
     of capital stock of DSI are, and all shares which may
     be issued will be, when issued, duly authorized,
     validly issued, fully paid and nonassessable and not
     subject to preemptive rights. As of the close of
     business on September 19, 1996, there were no bonds,
     debentures, notes or other indebtedness of DSI having
     the right to vote (or convertible into, or exchangeable
     for, securities having the right to vote) on any
     matters on which stockholders of DSI may vote. Except
     as set forth above or as contemplated by Schedule 5.07,
     as of the close of business on September 19, 1996,
     there were no outstanding securities, options,
     warrants, calls, rights, commitments, agreements,
     arrangements or undertakings of any kind to which DSI
     or any of its subsidiaries is a party or by which any
     of them is bound obligating DSI or any of its
     subsidiaries to issue, deliver or sell, or cause to be
     issued, delivered or sold, additional shares of capital
     stock or other voting securities of DSI or of any of
     its subsidiaries or obligating DSI or any of its
     subsidiaries to issue, grant, extend or enter into any
     such security, option, warrant, call, right,
     commitment, agreement, arrangement or undertaking.
     Except for agreements entered into with respect to the
     DSI Stock Plans, as of the close of business on
     September 19, 1996, there were no outstanding
     contractual obligations of DSI or any of its
     subsidiaries to repurchase, redeem or otherwise acquire
     any shares of capital stock of DSI or any of its wholly
     owned subsidiaries. As of the close of business on
     September 19, 1996, except for agreements with holders
     of equity securities of subsidiaries that are not
     wholly owned subsidiaries of DSI or any of its other
     wholly owned subsidiaries, there were no outstanding
     contractual obligations of DSI to vote or to dispose of
     any shares of the capital stock of any of its
     subsidiaries. DSI has delivered to UC a complete 
     and correct copy of the Rights Agreement, dated as of 


<PAGE>


     March 6, 1990 (the "DSI Rights Agreement"), as amended 
     and supplemented to the date hereof relating to rights
     ("DSI Rights") to purchase Junior Preferred Stock.

          (d) Authority; Noncontravention. DSI has all
     requisite corporate power and authority to enter into
     this Agreement and, subject to the DSI Stockholder
     Approval (as defined in Section 3.01(m)), to consummate
     the transactions contemplated by this Agreement. DSI
     has all requisite corporate power and authority to
     enter into the Option Agreements and to consummate the
     transactions contemplated thereby. The execution and
     delivery of this Agreement and the Option Agreements by
     DSI and the consummation by DSI of the transactions
     contemplated by this Agreement and the Option
     Agreements have been duly authorized by all necessary
     corporate action on the part of DSI, subject, in the
     case of the adoption of this Agreement, to DSI
     Stockholder Approval. This Agreement and the Option
     Agreements have been duly executed and delivered by DSI
     and constitute legal, valid and binding obligations of
     DSI, enforceable against DSI in accordance with their
     terms. The execution and delivery of this Agreement and
     the Option Agreements do not, and the consummation of
     the transactions contemplated by this Agreement and the
     Option Agreements and compliance with the provisions of
     this Agreement and the Option Agreements will not,
     conflict with, or result in any violation of, or
     default (with or without notice or lapse of time, or
     both) under, or give rise to a right of termination,
     cancelation or acceleration of any obligation or loss
     of a material benefit under, or result in the creation
     of any Lien upon any of the properties or assets of DSI
     or any of its Significant Subsidiaries under, (i) the
     certificate of incorporation or by-laws of DSI or the
     comparable organizational documents of any of its
     Significant Subsidiaries, (ii) any loan or credit
     agreement, note, bond, mortgage, indenture, lease or
     other agreement, instrument, permit, concession,
     franchise or license applicable to DSI or any of its
     Significant Subsidiaries or their respective properties
     or assets, or (iii) subject to the governmental filings
     and other matters referred to in the following
     sentence, any judgment, order, decree, statute, law,
     ordinance, rule or regulation applicable to DSI or any
     of its Significant Subsidiaries or their respective
     properties or assets, other than, in the case of
     clauses (ii) and (iii), any such conflicts, violations,


<PAGE>


     defaults, rights, losses or Liens that individually or
     in the aggregate would not (x) have a material adverse
     effect on DSI, (y) impair the ability of DSI to perform
     its obligations under this Agreement or the Option
     Agreements, or (z) prevent or materially delay the
     consummation of any of the transactions contemplated by
     this Agreement or the Option Agreements. No consent,
     approval, order or authorization of, or registration,
     declaration or filing with, any federal, state, local
     or foreign government or any court, administrative or
     regulatory agency or commission or other governmental
     authority or agency (a "Governmental Entity") is
     required by or with respect to DSI or any of its
     Significant Subsidiaries in connection with the
     execution and delivery of this Agreement or the Option
     Agreements by DSI or the consummation by DSI of the
     transactions contemplated by this Agreement or the
     Option Agreements, except for (1) the filing of a
     premerger notification and report form by DSI under the
     Hart-Scott-Rodino Antitrust Improvements Act of 1976,
     as amended (the "HSR Act"); (2) the filing with the SEC
     of (A) a proxy statement relating to the DSI
     Stockholders Meeting (as defined in Section 5.01(b))
     (such proxy statement, together with the proxy
     statement relating to the UC Stockholders Meeting (as
     defined in Section 5.01(c)), in each case as amended or
     supplemented from time to time, the "Joint Proxy
     Statement"), and (B) such reports under Section 13(a),
     13(d), 15(d) or 16(a) of the Securities Exchange Act of
     1934, as amended (the "Exchange Act"), as may be
     required in connection with this Agreement, the Option
     Agreements and the transactions contemplated by this
     Agreement and the Option Agreements; (3) the filing of
     the Certificate of Merger with the Delaware Secretary
     of State and appropriate documents with the relevant
     authorities of other states in which DSI is qualified
     to do business and such filings with Governmental
     Entities to satisfy the applicable requirements of
     state securities or "blue sky" laws; (4) such filings
     with and approvals of the NYSE to permit the shares of
     DSI Common Stock that are to be issued pursuant to the
     DSI Stock Option Agreement to be listed on the NYSE;
     (5) such other filings and consents as may be required
     under any environmental, health or safety law or
     regulation pertaining to any notification, disclosure
     or required approval necessitated by the Merger or the
     transactions contemplated by this Agreement and the
     Option Agreements; and (6) such consents, approvals,


<PAGE>


     orders or authorizations the failure of which to be
     made or obtained would not reasonably be expected to
     have a material adverse effect on DSI.

          (e) SEC Documents; Undisclosed Liabilities. DSI
     has filed all required reports, schedules, forms,
     statements and other documents with the SEC since
     January 1, 1995 (the "DSI SEC Documents"). As of their
     respective dates, the DSI SEC Documents complied in all
     material respects with the requirements of the
     Securities Act of 1933, as amended (the "Securities
     Act"), or the Exchange Act, as the case may be, and the
     rules and regulations of the SEC promulgated thereunder
     applicable to such DSI SEC Documents, and none of the
     DSI SEC Documents when filed contained any untrue
     statement of a material fact or omitted to state a
     material fact required to be stated therein or
     necessary in order to make the statements therein, in
     light of the circumstances under which they were made,
     not misleading. Except to the extent that information
     contained in any DSI SEC Document has been revised or
     superseded by a later DSI Filed SEC Document, none of
     the DSI SEC Documents contains any untrue statement of
     a material fact or omits to state any material fact
     required to be stated therein or necessary in order to
     make the statements therein, in light of the
     circumstances under which they were made, not
     misleading. The financial statements of DSI included in
     the DSI SEC Documents comply as to form, as of their
     respective dates of filing with the SEC, in all
     material respects with applicable accounting
     requirements and the published rules and regulations of
     the SEC with respect thereto, have been prepared in
     accordance with generally accepted accounting
     principles (except, in the case of unaudited
     statements, as permitted by Form 10-Q of the SEC)
     applied on a consistent basis during the periods
     involved (except as may be indicated in the notes
     thereto) and fairly present in all material respects
     the consolidated financial position of DSI and its
     consolidated subsidiaries as of the dates thereof and
     the consolidated results of their operations and cash
     flows for the periods then ended (subject, in the case
     of unaudited statements, to normal recurring year-end
     audit adjustments). Except (i) as reflected in such
     financial statements or in the notes thereto, (ii) as
     contemplated hereunder or under the Option Agreements,
     (iii) for liabilities incurred in connection with this


<PAGE>


     Agreement or the transactions contemplated hereby and
     (iv) for liabilities and obligations incurred since
     July 1, 1996 in the ordinary course of business
     consistent with past practice, neither DSI nor any of
     its subsidiaries has any material liabilities or
     obligations of any nature (whether accrued, absolute,
     contingent or otherwise), including liabilities arising
     under any laws relating to the protection of health,
     safety or the environment ("Environmental Laws"),
     required by generally accepted accounting principles to
     be reflected in a consolidated balance sheet of DSI and
     its consolidated subsidiaries and which, individually
     or in the aggregate, could reasonably be expected to
     have a material adverse effect on DSI.

          (f) Information Supplied. None of the information
     supplied or to be supplied by DSI specifically for
     inclusion or incorporation by reference in (i) the
     registration statement on Form S-4 to be filed with the
     SEC by UC in connection with the issuance of UC Common
     Stock and UC Convertible Preferred Stock in the Merger
     (the "Form S-4") will, at the time the Form S-4 is
     filed with the SEC or at the time it becomes effective
     under the Securities Act, contain any untrue statement
     of a material fact or omit to state any material fact
     required to be stated therein or necessary to make the
     statements therein not misleading or (ii) the Joint
     Proxy Statement will, at the date it is first mailed to
     DSI's stockholders or at the time of the DSI
     Stockholders Meeting, contain any untrue statement of a
     material fact or omit to state any material fact
     required to be stated therein or necessary in order to
     make the statements therein, in light of the
     circumstances under which they are made, not
     misleading. The Joint Proxy Statement will comply as to
     form in all material respects with the requirements of
     the Exchange Act and the rules and regulations
     thereunder, except that no representation or warranty
     is made by DSI with respect to statements made or
     incorporated by reference therein based on information
     supplied by UC specifically for inclusion or
     incorporation by reference in the Joint Proxy
     Statement.

          (g) Absence of Certain Changes or Events. Except
     (i) as disclosed in the DSI SEC Documents filed and
     publicly available prior to the date of this Agreement
     (as amended to the date of this Agreement, the "DSI


<PAGE>


     Filed SEC Documents"), (ii) for the transactions
     provided for herein or in the Option Agreements, and
     (iii) for liabilities incurred in connection with or as
     a result of this Agreement or the Option Agreements,
     since the date of the most recent audited financial
     statements included in the DSI Filed SEC Documents, DSI
     has conducted its business only in the ordinary course,
     and there has not been (1) any material adverse change
     in DSI, (2) any declaration, setting aside or payment
     of any dividend or other distribution (whether in cash,
     stock or property) with respect to any of DSI's capital
     stock, other than regular quarterly dividends of $.14
     per share on the DSI Common Stock and $.625 per share
     on the DSI Convertible Preferred Stock in accordance
     with the terms thereof, (3) any split, combination or
     reclassification of any of DSI's capital stock or any
     issuance or the authorization of any issuance of any
     other securities in respect of, in lieu of or in
     substitution for shares of DSI's capital stock, except
     for issuances of DSI Common Stock upon conversion of
     DSI Convertible Preferred Stock, (4) other than as
     permitted by Section 5.07, (A) any granting by DSI or
     any of its Significant Subsidiaries to any director,
     executive officer or other key employee of DSI of any
     increase in compensation, except for normal increases
     in the ordinary course of business consistent with past
     practice or as was required under employment agreements
     in effect as of the date of the most recent financial
     statements included in the DSI Filed SEC Documents, (B)
     any granting by DSI or any of its Significant
     Subsidiaries to any such director, executive officer or
     key employee of any increase in severance or
     termination pay, except as was required under any
     employment, severance or termination agreements in
     effect as of the date of the most recent financial
     statements included in the DSI Filed SEC Documents, or
     (C) any entry by DSI or any of its subsidiaries into
     any employment, severance or termination agreement with
     any such executive officer or key employee, or (5)
     except insofar as may have been disclosed in the DSI
     Filed SEC Documents or required by a change in
     generally accepted accounting principles, any change in
     accounting methods, principles or practices by DSI
     materially affecting its assets, liabilities or
     business. For purposes of this Agreement, "key
     employee" means any employee whose current salary and
     targeted bonus exceeds $100,000 per annum.


<PAGE>


          (h) Litigation. As of the date of this Agreement,
     there was no suit, action or proceeding pending or, to
     the knowledge of DSI, threatened against or affecting
     DSI or any of its subsidiaries that individually or in
     the aggregate could reasonably be expected to (i) have
     a material adverse effect on DSI or (ii) impair the
     ability of DSI to perform its obligations under this
     Agreement or the Option Agreements in any material
     respect, nor as of such date was there any judgment,
     order or decree of any Governmental Entity or
     arbitrator outstanding against DSI or any of its
     subsidiaries having, or which could reasonably be
     expected to have, any effect referred to in clause (i)
     or (ii) above.

          (i) Compliance with Applicable Laws. DSI and its
     subsidiaries hold all permits, licenses, variances,
     exemptions, orders and approvals of all Governmental
     Entities which are material to the operation of the
     businesses of DSI and its subsidiaries, taken as a
     whole (the "DSI Permits"). DSI and its subsidiaries are
     in compliance with the terms of the DSI Permits and all
     applicable statutes, laws, ordinances, rules and
     regulations, including Environmental Laws, except where
     the failure so to comply, individually or in the
     aggregate, could not reasonably be expected to have a
     material adverse effect on DSI. The businesses of DSI
     and its subsidiaries are not being conducted in
     violation of any law, ordinance or regulation of any
     Governmental Entity, including Environmental Laws,
     except for possible violations which could not
     reasonably be expected to have a material adverse
     effect on DSI. As of the date of this Agreement, no
     action, demand, requirement or investigation by any
     Governmental Entity with respect to DSI or any of its
     subsidiaries is pending or, to the knowledge of DSI,
     threatened, other than, in each case, those the outcome
     of which, individually or in the aggregate, could not
     reasonably be expected to have a material adverse
     effect on DSI.

          (j) Absence of Changes in Benefit Plans. Since 
     the date of the most recent financial statements
     included in the DSI Filed SEC Documents, there has not
     been any adoption or amendment in any material respect
     by DSI or any of its subsidiaries of any collective
     bargaining agreement or any bonus, pension, profit
     sharing, deferred compensation, incentive compensation,


<PAGE>


     stock ownership, stock purchase, stock option, phantom
     stock, retirement, vacation, severance, disability,
     death benefit, hospitalization, medical or other plan,
     arrangement or understanding (whether or not legally
     binding) providing benefits to any current or former
     employee, officer or director of DSI or any of its
     wholly owned subsidiaries. Except as permitted by
     Section 5.07, since the date of the most recent
     financial statements included in the DSI Filed SEC
     Documents, neither DSI nor any of its wholly owned
     subsidiaries has entered into any employment,
     consulting, severance, termination or indemnification
     agreements, arrangements or understandings with any
     current or former employee, officer or director of DSI
     or any of its wholly owned subsidiaries.

          (k) ERISA Compliance. (i) With respect to each
     employee benefit plan (including, without limitation,
     any "employee benefit plan", as defined in Section 3(3)
     of the Employee Retirement Income Security Act of 1974,
     as amended ("ERISA")) (all the foregoing being herein
     called "Benefit Plans"), maintained or contributed to
     by DSI or any subsidiary of DSI (the "DSI Benefit
     Plans"), DSI has made available to UC a true and
     correct copy of (A) the most recent annual report (Form
     5500) filed with the IRS, (B) such DSI Benefit Plans,
     (C) each trust agreement relating to such DSI Benefit
     Plans, (D) the most recent summary plan description for
     each DSI Benefit Plans for which a summary plan
     description is required, (E) the most recent actuarial
     report or valuation relating to DSI Benefit Plans
     subject to Title IV of ERISA, and (F) the most recent
     determination letter issued by the IRS with respect to
     any DSI Benefit Plans qualified under Section 401(a) of
     the Code.

          (ii) With respect to the DSI Benefit Plans,
     individually and in the aggregate, no event has
     occurred and, to the knowledge of DSI, there exists no
     condition or set of circumstances, in connection with
     which DSI or any of its subsidiaries could be subject
     to any liability that is reasonably likely to have a
     material adverse effect on DSI (except liability for
     benefits claims and funding obligations payable in the
     ordinary course) under ERISA, the Code or any other
     applicable law.


<PAGE>


          (iii) Each DSI Benefit Plan has been administered
     in accordance with its terms except for any failures so
     to administer any DSI Benefit Plan as would not
     individually or in the aggregate have a material
     adverse effect on DSI. DSI, its subsidiaries and all
     the DSI Benefit Plans are in compliance with the
     applicable provisions of ERISA, the Code and all other
     applicable laws and the terms of all applicable
     collective bargaining agreements, except for any
     failures to be in such compliance as would not
     individually or in the aggregate have a material
     adverse effect on DSI.

          (iv) No employee of DSI will be entitled to any
     additional benefits or any acceleration of the time of
     payment or vesting of any benefits under any DSI
     Benefit Plan as a result of the transactions
     contemplated by this Agreement or the Option
     Agreements.

          (l) Taxes. (i) Each of DSI and its subsidiaries
     has filed all tax returns and reports required to be
     filed by it or requests for extensions to file such
     returns or reports have been timely filed, granted and
     have not expired, except to the extent that such
     failures to file or to have extensions granted that
     remain in effect individually or in the aggregate would
     not have a material adverse effect on DSI. DSI and each
     of its subsidiaries has paid (or DSI has paid on its
     behalf) all taxes shown as due on such returns, and the
     most recent financial statements contained in the DSI
     Filed SEC Documents reflect an adequate reserve for all
     taxes payable by DSI and its subsidiaries for all
     taxable periods and portions thereof accrued through
     the date of such financial statements.

          (ii) No deficiencies for any taxes have been
     proposed, asserted or assessed against DSI or any of
     its subsidiaries that are not adequately reserved for,
     except for deficiencies that individually or in the
     aggregate would not have a material adverse effect on
     DSI. The federal income tax returns of DSI and each of
     its subsidiaries consolidated in such returns have
     closed by virtue of the applicable statute of
     limitations or remain open for the periods described in
     the DSI Disclosure Schedule.


<PAGE>

          (iii) Neither DSI nor any of its subsidiaries has
     taken any action that is reasonably likely to prevent
     the Merger from qualifying as a reorganization within
     the meaning of Section 368(a) of the Code.

          (iv) As used in this Agreement, "taxes" shall
     include all federal, state and local income, property,
     sales, excise and other taxes or similar governmental
     charges.

          (m) Voting Requirements. The affirmative vote of
     the holders of a majority of the voting power of all
     outstanding shares of DSI Common Stock, voting as a
     single class, at the DSI Stockholders Meeting (the "DSI
     Stockholder Approval") to adopt this Agreement is the
     only vote of the holders of any class or series of
     DSI's capital stock necessary to approve and adopt this
     Agreement, the Option Agreements and the transactions
     contemplated by this Agreement and the Option
     Agreements.

          (n) State Takeover Statutes. The Board of
     Directors of DSI has approved the terms of this
     Agreement and the Option Agreements and the
     consummation of the Merger and the other transactions
     contemplated by this Agreement and the Option
     Agreements and, assuming the accuracy of UC's
     representation and warranty contained in Section
     3.02(n), such approval constitutes approval of the
     Merger and the other transactions contemplated by this
     Agreement and the Option Agreements by the DSI Board of
     Directors under the provisions of Section 203 of the
     DGCL.

          (o) Accounting Matters. Neither DSI nor any of its
     affiliates has taken or agreed to take any action that
     would prevent the business combination to be effected
     by the Merger to be accounted for as a pooling of
     interests.

          (p) Brokers. No broker, investment banker,
     financial advisor or other person, other than
     Wasserstein Perella & Co., Inc., the fees and expenses
     of which will be paid by DSI or, if the Merger occurs,
     the Surviving Corporation, is entitled to any broker's,
     finder's, financial advisor's or other similar fee or
     commission in connection with the transactions
     contemplated by this Agreement and the Option


<PAGE>


     Agreements based upon arrangements made by or on behalf
     of DSI. DSI has furnished to UC true and complete
     copies of all agreements under which any such fees or
     expenses are payable and all indemnification and other
     agreements related to the engagement of the persons to
     whom such fees are payable.

          (q) Opinion of Financial Advisor. DSI has received
     the opinion of Wasserstein Perella & Co., Inc., dated
     the date of this Agreement, to the effect that, as of
     such date, the exchange ratio for the conversion of DSI
     Common Stock into UC Common Stock pursuant to the
     Merger is fair to DSI's stockholders from a financial
     point of view, a signed copy of which opinion has been
     delivered to UC.

          (r) Ownership of UC Common Stock. Other than
     pursuant to the UC Stock Option Agreement and except
     for shares owned by DSI Benefit Plans, as of the date
     hereof, neither DSI nor, to its knowledge, any of its
     affiliates, (i) beneficially owns (as such term is
     defined in Rule 13d-3 under the Exchange Act), directly
     or indirectly, or (ii) is party to any agreement,
     arrangement or understanding for the purpose of
     acquiring, holding, voting or disposing of, in each
     case, shares of capital stock of UC.

          (s) DSI Rights Agreement. The DSI Rights 
     Agreement has been amended (the "DSI Rights Plan
     Amendment") to (i) render the DSI Rights Agreement
     inapplicable to the Merger and the other transactions
     contemplated by this Agreement and the Option
     Agreements and (ii) ensure that (y) neither UC nor any
     of its wholly owned subsidiaries nor any of its
     permitted assignees or transferees under the DSI Stock
     Option Agreement is an Acquiring Person or an Adverse
     Person (each as defined in the DSI Rights Agreement)
     pursuant to the DSI Rights Agreement and (z) a Share
     Acquisition Date, Distribution Date or Triggering Event
     (in each case as defined in the DSI Rights Agreement)
     does not occur solely by reason of the execution of
     this Agreement, and the Option Agreements, the
     consummation of the Merger, or the consummation of the
     other transactions contemplated by this Agreement and
     the Option Agreements and such amendment may not be
     further amended by DSI without the prior consent of UC
     in its sole discretion. A copy of a form of the DSI


<PAGE>


     Rights Plan Amendment is attached to the DSI Disclosure
     Schedule.

          SECTION 3.02. Representations and Warranties of
UC. Except as disclosed in the UC Filed SEC Documents (as
such term is defined in Section 3.02(g)) or as set forth on
the Disclosure Schedule delivered by UC to DSI prior to the
execution of this Agreement (the "UC Disclosure Schedule"),
UC represents and warrants to DSI as follows:

          (a) Organization, Standing and Corporate Power.
     Each of UC and its Significant Subsidiaries is a
     corporation or other legal entity duly organized,
     validly existing and in good standing (with respect to
     jurisdictions which recognize such concept) under the
     laws of the jurisdiction in which it is organized and
     has the requisite corporate or other power, as the case
     may be, and authority to carry on its business as now
     being conducted. Each of UC and its Significant
     Subsidiaries is duly qualified or licensed to do
     business and is in good standing (with respect to
     jurisdictions which recognize such concept) in each
     jurisdiction in which the nature of its business or the
     ownership or leasing of its properties makes such
     qualification or licensing necessary, other than in
     such jurisdictions where the failure to be so qualified
     or licensed or to be in good standing individually or
     in the aggregate would not have a material adverse
     effect on UC. UC has delivered to DSI prior to the
     execution of this Agreement complete and correct copies
     of its certificate of incorporation and by-laws and has
     made available to DSI the certificates of incorporation
     and by-laws (or comparable organizational documents) of
     its Significant Subsidiaries, in each case as amended
     to date.

          (b) Subsidiaries. Exhibit 21 to UC's Annual Report
     on Form 10-K for the fiscal year ended December 31,
     1995 includes all the subsidiaries of UC which as of
     the date of this Agreement are Significant
     Subsidiaries. All the outstanding shares of capital
     stock of, or other equity interests in, each such
     Significant Subsidiary have been validly issued and are
     fully paid and nonassessable and are owned directly or
     indirectly by UC, free and clear of all Liens.

          (c) Capital Structure. The authorized capital
     stock of UC consists of 100,000,000 shares of UC Common


<PAGE>


     Stock and 25,000,000 shares of preferred stock, par
     value $.01 per share, of UC ("UC Preferred Stock"). At
     the close of business on September 19, 1996, 
     (i) 44,637,958 shares of UC Common Stock were issued
     and outstanding, (ii) no shares of UC Common Stock were
     held by UC in its treasury, (iii) 6,137,103 shares of
     UC Common Stock were reserved for issuance pursuant to
     the Ultramar Corporation Annual Incentive Plan, the
     Ultramar Corporation Dividend Reinvestment, the
     Ultramar Corporation Restricted Share Plan for
     Directors and Employee Stock Purchase Plan and the
     Ultramar Corporation 1992 Long Term Incentive Plan
     (such plans, collectively, the "UC Stock Plans"), and
     (iv) no shares of UC Preferred Stock have been
     designated or issued. Except as set forth above and
     except for 8,927,500 shares of UC Common Stock (with
     the associated UC Rights) reserved for issuance upon
     the exercise of the UC Option, at the close of business
     on September 19, 1996, no shares of capital stock or
     other voting securities of UC were issued, reserved for
     issuance or outstanding. At the close of business on
     September 19, 1996 there were no outstanding stock
     appreciation rights or rights (other than employee
     stock options or other rights ("UC Employee Stock
     Options") to purchase or receive UC Common Stock
     granted under the UC Stock Plans) to receive shares of
     UC Common Stock on a deferred basis granted under the
     UC Stock Plans or otherwise. The UC Disclosure 
     Schedule sets forth a complete and correct list, as of
     September 19, 1996, of the number of shares of UC
     Common Stock subject to Employee Stock Options and the
     exercise prices thereof. All outstanding shares of
     capital stock of UC are, and all shares which may be
     issued will be, when issued, duly authorized, validly
     issued, fully paid and nonassessable and not subject to
     preemptive rights. As of the close of business on
     September 19, 1996, there were no bonds, debentures,
     notes or other indebtedness of UC having the right to
     vote (or convertible into, or exchangeable for,
     securities having the right to vote) on any matters on
     which stockholders of UC may vote. Except as set forth
     above or as contemplated by Schedule 5.07, as of the
     close of business on September 19, 1996, there were no
     outstanding securities, options, warrants, calls,
     rights, commitments, agreements, arrangements or
     undertakings of any kind to which UC or any of its
     subsidiaries is a party or by which any of them is
     bound obligating UC or any of its subsidiaries to


<PAGE>


     issue, deliver or sell, or cause to be issued,
     delivered or sold, additional shares of capital stock
     or other voting securities of UC or of any of its
     subsidiaries or obligating UC or any of its
     subsidiaries to issue, grant, extend or enter into any
     such security, option, warrant, call, right,
     commitment, agreement, arrangement or undertaking.
     Except for agreements entered into with respect to the
     UC Stock Plans, as of the close of business on
     September 19, 1996, there were no outstanding
     contractual obligations of UC or any of its
     subsidiaries to repurchase, redeem or otherwise acquire
     any shares of capital stock of UC or any of its wholly
     owned subsidiaries. As of the close of business on
     September 19, 1996, except for agreements with holders
     of equity securities of subsidiaries that are not
     wholly owned subsidiaries of UC or any of its other
     wholly owned subsidiaries, there were no outstanding
     contractual obligations of UC to vote or to dispose of
     any shares of the capital stock of any of its
     subsidiaries. UC has delivered to DSI a complete and
     correct copy of the Rights Agreement dated as of June
     25, 1992, as amended as of May 10, 1994 (the "UC Rights
     Agreement") between UC and Registrar and Transfer
     Company (as successor to First City, Texas- Houston,
     National Association) relating to rights ("UC Rights")
     to purchase UC Common Stock.

          (d) Authority; Noncontravention. UC has all
     requisite corporate power and authority to enter into
     this Agreement and, subject to the UC Stockholder
     Approval (as defined in Section 3.02(m)), to consummate
     the transactions contemplated by this Agreement. UC 
     has all requisite corporate power and authority to
     enter into the Option Agreements and to consummate the
     transactions contemplated thereby. The execution and
     delivery of this Agreement and the Option Agreements by
     UC and the consummation by UC of the transactions
     contemplated by this Agreement and the Option
     Agreements have been duly authorized by all necessary
     corporate action on the part of UC, subject, in the
     case of the adoption of this Agreement and the issuance
     of UC Common Stock in connection with the Merger, to UC
     Stockholder Approval. This Agreement and the Option
     Agreements have been duly executed and delivered by UC
     and constitute legal, valid and binding obligations of
     UC, enforceable against UC in accordance with their
     terms. The execution and delivery of this Agreement and


<PAGE>


     the Option Agreements do not, and the consummation of
     the transactions contemplated by this Agreement and the
     Option Agreements and compliance with the provisions of
     this Agreement and the Option Agreements will not,
     conflict with, or result in any violation of, or
     default (with or without notice or lapse of time, or
     both) under, or give rise to a right of termination,
     cancelation or acceleration of any obligation or loss
     of a material benefit under, or result in the creation
     of any Lien upon any of the properties or assets of UC
     or any of its Significant Subsidiaries under, (i) the
     certificate of incorporation or by-laws of UC or the
     comparable organizational documents of any of its
     Significant Subsidiaries, (ii) any loan or credit
     agreement, note, bond, mortgage, indenture, lease or
     other agreement, instrument, permit, concession,
     franchise or license applicable to UC or any of its
     Significant Subsidiaries or their respective properties
     or assets, or (iii) subject to the governmental filings
     and other matters referred to in the following
     sentence, any judgment, order, decree, statute, law,
     ordinance, rule or regulation applicable to UC or any
     of its Significant Subsidiaries or their respective
     properties or assets, other than, in the case of
     clauses (ii) and (iii), any such conflicts, violations,
     defaults, rights, losses or Liens that individually or
     in the aggregate would not (x) have a material adverse
     effect on UC, (y) impair the ability of UC to perform
     its obligations under this Agreement or the Option
     Agreements, or (z) prevent or materially delay the
     consummation of any of the transactions contemplated by
     this Agreement or the Option Agreements. No consent,
     approval, order or authorization of, or registration,
     declaration or filing with, any Governmental Entity is
     required by or with respect to UC or any of its
     Significant Subsidiaries in connection with the
     execution and delivery of this Agreement or the Option
     Agreements by UC or the consummation by UC of the
     transactions contemplated by this Agreement or the
     Option Agreements, except for (1) the filing of a
     premerger notification and report form by UC under the
     HSR Act; (2) the filing with the SEC of (A) the Joint
     Proxy Statement relating to the UC Stockholders Meeting
     (as defined in Section 5.01(c)), (B) the Form S-4 and
     (C) such reports under Section 13(a), 13(d), 15(d) or
     16(a) of the Exchange Act as may be required in
     connection with this Agreement, the Option Agreements
     and the transactions contemplated by this Agreement and


<PAGE>


     the Option Agreements; (3) the filing of the
     Certificate of Merger and the Certificate of
     Designations with respect to the UC Convertible
     Preferred Stock with the Delaware Secretary of State
     and appropriate documents with the relevant authorities
     of other states in which UC is qualified to do business
     and such filings with Governmental Entities to satisfy
     the applicable requirements of state securities or
     "blue sky" laws; (4) such filings with and approvals of
     the NYSE to permit the shares of UC Common Stock that
     are to be issued in the Merger, under the DSI Stock
     Plans and pursuant to the UC Stock Option Agreement to
     be listed on the NYSE; (5) such other filings and
     consents as may be required under any environmental,
     health or safety law or regulation pertaining to any
     notification, disclosure or required approval
     necessitated by the Merger or the transactions
     contemplated by this Agreement and the Option
     Agreements; and (6) such consents, approvals, orders or
     authorizations the failure of which to be made or
     obtained would not reasonably be expected to have a
     material adverse effect on UC.

          (e) SEC Documents; Undisclosed Liabilities. UC has
     filed all required reports, schedules, forms,
     statements and other documents with the SEC since
     January 1, 1995 (the "UC SEC Documents"). As of their
     respective dates, the UC SEC Documents complied in all
     material respects with the requirements of the
     Securities Act or the Exchange Act, as the case may be,
     and the rules and regulations of the SEC promulgated
     thereunder applicable to such UC SEC Documents, and
     none of the UC SEC Documents when filed contained any
     untrue statement of a material fact or omitted to state
     a material fact required to be stated therein or
     necessary in order to make the statements therein, in
     light of the circumstances under which they were made,
     not misleading. Except to the extent that information
     contained in any UC SEC Document has been revised or
     superseded by a later UC Filed SEC Document, none of
     the UC SEC Documents contains any untrue statement of a
     material fact or omits to state any material fact
     required to be stated therein or necessary in order to
     make the statements therein, in light of the
     circumstances under which they were made, not
     misleading. The financial statements of UC included in
     the UC SEC Documents comply as to form, as of their
     respective dates of filing with the SEC, in all


<PAGE>


     material respects with applicable accounting
     requirements and the published rules and regulations of
     the SEC with respect thereto, have been prepared in
     accordance with generally accepted accounting
     principles (except, in the case of unaudited
     statements, as permitted by Form 10-Q of the SEC)
     applied on a consistent basis during the periods
     involved (except as may be indicated in the notes
     thereto) and fairly present in all material respects
     the consolidated financial position of UC and its
     consolidated subsidiaries as of the dates thereof and
     the consolidated results of their operations and cash
     flows for the periods then ended (subject, in the case
     of unaudited statements, to normal recurring year-end
     audit adjustments). Except (i) as reflected in such
     financial statements or in the notes thereto, (ii) as
     contemplated hereunder or under the Option Agreements,
     (iii) for liabilities incurred in connection with this
     Agreement or the transactions contemplated hereby and
     (iv) for liabilities and obligations incurred since
     July 1, 1996 in the ordinary course of business
     consistent with past practice, neither UC nor any of
     its subsidiaries has any material liabilities or
     obligations of any nature (whether accrued, absolute,
     contingent or otherwise), including liabilities arising
     under any Environmental Laws, required by generally
     accepted accounting principles to be reflected in a
     consolidated balance sheet of UC and its consolidated
     subsidiaries and which, individually or in the
     aggregate, could reasonably be expected to have a
     material adverse effect on UC.

          (f) Information Supplied. None of the 
     information supplied or to be supplied by UC
     specifically for inclusion or incorporation by
     reference in (i) the Form S-4 will, at the time the
     Form S-4 is filed with the SEC or at the time it
     becomes effective under the Securities Act, contain any
     untrue statement of a material fact or omit to state
     any material fact required to be stated therein or
     necessary to make the statements therein not misleading
     or (ii) the Joint Proxy Statement will, at the date it
     is first mailed to UC's stockholders or at the time of
     the UC Stockholders Meeting, contain any untrue
     statement of a material fact or omit to state any
     material fact required to be stated therein or
     necessary in order to make the statements therein, in
     light of the circumstances under which they are made,


<PAGE>


     not misleading. The Joint Proxy Statement will comply
     as to form in all material respects with the
     requirements of the Exchange Act and the rules and
     regulations thereunder, except that no representation
     or warranty is made by UC with respect to statements
     made or incorporated by reference therein based on
     information supplied by DSI specifically for inclusion
     or incorporation by reference in the Joint Proxy
     Statement.

     (g) Absence of Certain Changes or Events. Except (i) as
     disclosed in the UC SEC Documents filed and publicly
     available prior to the date of this Agreement (as
     amended to the date of this Agreement, the "UC Filed
     SEC Documents"), (ii) for the transactions provided for
     herein or in the Option Agreements, and (iii) for
     liabilities incurred in connection with or as a result
     of this Agreement or the Option Agreements, since the
     date of the most recent financial statements included
     in the UC Filed SEC Documents, UC has conducted its
     business only in the ordinary course, and there has not
     been (1) any material adverse change in UC, (2) any
     declaration, setting aside or payment of any dividend
     or other distribution (whether in cash, stock or
     property) with respect to any of UC's capital stock,
     other than regular quarterly dividends of $.275 per
     share on the UC Common Stock, (3) any split,
     combination or reclassification of any of UC's capital
     stock or any issuance or the authorization of any
     issuance of any other securities in respect of, in lieu
     of or in substitution for shares of UC's capital stock,
     (4) other than as permitted by Section 5.07, (A) any
     granting by UC or any of its Significant Subsidiaries
     to any director, executive officer or other key
     employee of UC of any increase in compensation, except
     for normal increases in the ordinary course of business
     consistent with past practice or as was required under
     employment agreements in effect as of the date of the
     most recent financial statements included in the UC
     Filed SEC Documents, (B) any granting by UC or any of
     its Significant Subsidiaries to any such director,
     executive officer or key employee of any increase in
     severance or termination pay, except as was required
     under any employment, severance or termination
     agreements in effect as of the date of the most recent
     financial statements included in the UC Filed SEC
     Documents, or (C) any entry by UC or any of its
     subsidiaries into any employment, severance or


<PAGE>


     termination agreement with any such executive officer
     or key employee or (5) except insofar as may have been
     disclosed in the UC Filed SEC Documents or required by
     a change in generally accepted accounting principles,
     any change in accounting methods, principles or
     practices by UC materially affecting its assets,
     liabilities or business.

          (h) Litigation. As of the date of this Agreement,
     there was no suit, action or proceeding pending or, to
     the knowledge of UC, threatened against or affecting UC
     or any of its subsidiaries that individually or in the
     aggregate could reasonably be expected to (i) have a
     material adverse effect on UC or (ii) impair the
     ability of UC to perform its obligations under this
     Agreement or the Option Agreements in any material
     respect, nor as of such date was there any judgment,
     order or decree of any Governmental Entity or
     arbitrator outstanding against UC or any of its
     subsidiaries having, or which could reasonably be
     expected to have, any effect referred to in clause (i)
     or (ii) above.

          (i) Compliance with Applicable Laws. UC and its
     subsidiaries hold all permits, licenses, variances,
     exemptions, orders and approvals of all Governmental
     Entities which are material to the operation of the
     businesses of UC and its subsidiaries, taken as a whole
     (the "UC Permits"). UC and its subsidiaries are in
     compliance with the terms of the UC Permits and all
     applicable statutes, laws, ordinances, rules and
     regulations, including Environmental Laws, except where
     the failure so to comply, individually or in the
     aggregate, could not reasonably be expected to have a
     material adverse effect on UC. The businesses of UC and
     its subsidiaries are not being conducted in violation
     of any law, ordinance or regulation of any Governmental
     Entity, including Environmental Laws, except for
     possible violations which could not reasonably be
     expected to have a material adverse effect on UC. As of
     the date of this Agreement, no action, demand,
     requirement or investigation by any Governmental Entity
     with respect to UC or any of its subsidiaries is
     pending or, to the knowledge of UC, threatened, other
     than, in each case, those the outcome of which,
     individually or in the aggregate could not reasonably
     be expected to have a material adverse effect on UC.


<PAGE>


          (j) Absence of Changes in Benefit Plans. Since the
     date of the most recent financial statements included
     in the UC Filed SEC Documents, there has not been any
     adoption or amendment in any material respect by UC or
     any of its subsidiaries of any collective bargaining
     agreement or any bonus, pension, profit sharing,
     deferred compensation, incentive compensation, stock
     ownership, stock purchase, stock option, phantom stock,
     retirement, vacation, severance, disability, death
     benefit, hospitalization, medical or other plan,
     arrangement or understanding (whether or not legally
     binding) providing benefits to any current or former
     employee, officer or director of UC or any of its
     wholly owned subsidiaries. Except as permitted by
     Section 5.07, since the date of the most recent
     financial statements included in the UC Filed SEC
     Documents, neither UC nor any of its wholly owned
     subsidiaries has entered into any employment,
     consulting, severance, termination or indemnification
     agreements, arrangements or understandings with any
     current or former employee, officer or director of UC
     or any of its wholly owned subsidiaries.

          (k) ERISA Compliance. (i) With respect to Benefit
     Plans maintained or contributed to by UC or any
     subsidiary of UC (the "UC Benefit Plans"), UC has made
     available to DSI a true and correct copy of (A) the
     most recent annual report (Form 5500) filed with the
     IRS, (B) such UC Benefit Plans, (C) each trust
     agreement relating to such UC Benefit Plans, (D) the
     most recent summary plan description for each UC
     Benefit Plans for which a summary plan description is
     required, (E) the most recent actuarial report or
     valuation relating to UC Benefit Plans subject to Title
     IV of ERISA, and (F) the most recent determination
     letter issued by the IRS with respect to any UC Benefit
     Plans qualified under Section 401(a) of the Code.

          (ii) With respect to the UC Benefit Plans,
     individually and in the aggregate, no event has
     occurred and, to the knowledge of UC, there exists no
     condition or set of circumstances, in connection with
     which UC or any of its subsidiaries could be subject to
     any liability that is reasonably likely to have a
     material adverse effect on UC (except liability for
     benefits claims and funding obligations payable in the


<PAGE>


     ordinary course) under ERISA, the Code or any other
     applicable law.

          (iii) Each UC Benefit Plan has been administered
     in accordance with its terms, except for any failures
     so to administer any UC Benefit Plans as would not
     individually or in the aggregate have a material
     adverse effect on UC. UC, its subsidiaries and all the
     UC Benefit Plans are in compliance with the applicable
     provisions of ERISA, the Code and all other applicable
     laws and the terms of all applicable collective
     bargaining agreements, except for any failures to be in
     such compliance as would not individually or in the
     aggregate have a material adverse effect on UC.

          (iv) No employee of UC will be entitled to any
     additional benefits or any acceleration of the time of
     payment or vesting of any benefits under any UC Benefit
     Plan as a result of the transactions contemplated by
     this Agreement or the Option Agreements.

          (l) Taxes. (i) Each of UC and its subsidiaries has
     filed all tax returns and reports required to be filed
     by it or requests for extensions to file such returns
     or reports have been timely filed, granted and have not
     expired, except to the extent that such failures to
     file or to have extensions granted that remain in
     effect individually or in the aggregate would not have
     a material adverse effect on UC. UC and each of its
     subsidiaries has paid (or UC has paid on its behalf)
     all taxes shown as due on such returns, and the most
     recent financial statements contained in the UC Filed
     SEC Documents reflect an adequate reserve for all taxes
     payable by UC and its subsidiaries for all taxable
     periods and portions thereof accrued through the date
     of such financial statements.

          (ii) No deficiencies for any taxes have been
     proposed, asserted or assessed against UC or any of its
     subsidiaries that are not adequately reserved for,
     except for deficiencies that individually or in the
     aggregate would not have a material adverse effect on
     UC.

          (iii) Neither UC nor any of its subsidiaries has
     taken any action that is reasonably likely to prevent
     the Merger from qualifying as a reorganization within
     the meaning of Section 368(a) of the Code.


<PAGE>


          (m) Voting Requirements. The affirmative vote of
     the holders of a majority of the voting power of all
     outstanding shares of UC Common Stock, voting as a
     single class, at the UC Stockholders Meeting (the "UC
     Stockholder Approval") to adopt this Agreement and to
     approve the issuance of UC Common Stock in connection
     with the Merger is the only vote of the holders of any
     class or series of UC's capital stock necessary to
     approve and adopt this Agreement, the Option Agreements
     and the transactions contemplated by this Agreement and
     the Option Agreements.

          (n) State Takeover Statutes. The Board of
     Directors of UC has approved the terms of this
     Agreement and the Option Agreements and the
     consummation of the Merger and the other transactions
     contemplated by this Agreement and the Option
     Agreements and, assuming the accuracy of DSI's
     representation and warranty contained in Section
     3.01(n), such approval constitutes approval of the
     Merger and the other transactions contemplated by this
     Agreement and the Option Agreements by the UC Board of
     Directors under the provisions of Section 203 of the
     DGCL.

          (o) Accounting Matters. Neither UC nor any of its
     affiliates has taken or agreed to take any action that
     would prevent the business combination to be effected
     by the Merger to be accounted for as a pooling of
     interests.

          (p) Brokers. No broker, investment banker,
     financial advisor or other person, other than Merrill
     Lynch & Co. and Tanner & Co., Inc., the fees and
     expenses of which will be paid by UC or, if the Merger
     occurs, the Surviving Corporation, is entitled to any
     broker's, finder's, financial advisor's or other
     similar fee or commission in connection with the
     transactions contemplated by this Agreement and the
     Option Agreements based upon arrangements made by or on
     behalf of UC. UC has furnished to DSI true and complete
     copies of all agreements under which any such fees or
     expenses are payable and all indemnification and other
     agreements related to the engagement of the persons to
     whom such fees are payable.

          (q) Opinion of Financial Advisor. UC has 
     received the opinion of Merrill Lynch & Co., dated the


<PAGE>


     date of this Agreement, to the effect that, as of such
     date, the exchange ratio for the conversion of DSI
     Common Stock into UC Common Stock pursuant to the
     Merger is fair to UC and, accordingly, to UC's
     stockholders from a financial point of view, a signed
     copy of which opinion has been delivered to DSI.

          (r) Ownership of DSI Common Stock. Other than
     pursuant to the DSI Stock Option Agreement and except
     for shares owned by UC Benefit Plans, as of the date
     hereof, neither UC nor, to its knowledge, any of its
     affiliates, (i) beneficially owns (as such term is
     defined in Rule 13d-3 under the Exchange Act), directly
     or indirectly, or (ii) is party to any agreement,
     arrangement or understanding for the purpose of
     acquiring, holding, voting or disposing of, in each
     case, shares of capital stock of DSI.

          (s) UC Rights Agreement. The UC Rights Agreement
     has been amended (the "UC Rights Plan Amendment") to
     (i) render the UC Rights Agreement inapplicable to the
     Merger and the other transactions contemplated by this
     Agreement and the Option Agreements and (ii) ensure
     that (y) neither DSI nor any of its wholly owned
     subsidiaries nor any of its permitted assignees or
     transferees under the UC Stock Option Agreement is an
     Acquiring Person (as defined in the UC Rights
     Agreement) pursuant to the UC Rights Agreement and (z)
     a Distribution Date (as defined in the UC Rights
     Agreement) does not occur solely by reason of the
     execution of this Agreement and the Option Agreements,
     the consummation of the Merger, or the consummation of
     the other transactions contemplated by this Agreement
     and the Option Agreements and such amendment may not be
     further amended by UC without the prior consent of DSI
     in its sole discretion. A copy of a form of the UC
     Rights Plan Amendment is attached to the UC Disclosure
     Schedule.


                         ARTICLE IV

          Covenants Relating to Conduct of Business

          SECTION 4.01. Conduct of Business. (a) Conduct 
of Business by DSI. Except as set forth in Section 4.01 of
the DSI Disclosure Schedule, during the period from the date
of this Agreement to the Effective Time, DSI shall, and


<PAGE>


shall cause its subsidiaries to, carry on their respective
businesses in the usual, regular and ordinary course in
substantially the same manner as heretofore conducted and in
compliance in all material respects with all applicable laws
and regulations and, to the extent consistent therewith, use
all reasonable efforts to preserve intact their current
business organizations, use reasonable efforts to keep
available the services of their current officers and other
key employees and preserve their relationships with those
persons having business dealings with them to the end that
their goodwill and ongoing businesses shall be unimpaired at
the Effective Time. Except as set forth in Section 4.01 of
the DSI Disclosure Schedule, without limiting the generality
of the foregoing, during the period from the date of this
Agreement to the Effective Time, DSI shall not, and shall
not permit any of its subsidiaries to:

          (i) other than dividends and distributions
     (including liquidating distributions) by a direct or
     indirect wholly owned subsidiary of DSI to its parent,
     or by a subsidiary that is partially owned by DSI or
     any of its subsidiaries, provided that DSI or any such
     subsidiary receives or is to receive its proportionate
     share thereof, and other than the regular quarterly
     dividends of $.14 per share with respect to the DSI
     Common Stock and regular quarterly dividends of $.625
     per share with respect to the DSI Convertible Preferred
     Stock in accordance with its terms, (x) declare, set
     aside or pay any dividends on, or make any other
     distributions in respect of, any of its capital stock,
     (y) split, combine or reclassify any of its capital
     stock or issue or authorize the issuance of any other
     securities in respect of, in lieu of or in substitution
     for shares of its capital stock, or (z) purchase,
     redeem or otherwise acquire any shares of capital stock
     of DSI or any of its Significant Subsidiaries or any
     other securities thereof or any rights, warrants or
     options to acquire any such shares or other securities;

          (ii) issue, deliver, sell, pledge or otherwise
     encumber any shares of its capital stock, any other
     voting securities or any securities convertible into,
     or any rights, warrants or options to acquire, any such
     shares, voting securities or convertible securities
     (other than (x) the issuance of DSI Common Stock upon
     the exercise of DSI Employee Stock Options outstanding
     on the date of this Agreement and in accordance with
     their present terms, (y) the issuance of DSI Common


<PAGE>


     Stock upon conversion of DSI Convertible Preferred
     Stock in accordance with their present terms either at
     the option of the holders thereof or at the option of
     DSI, and (z) the issuance of DSI Common Stock pursuant
     to the DSI Stock Option Agreement);

          (iii) amend its certificate of incorporation,
     by-laws or other comparable organizational documents;

          (iv) acquire or agree to acquire by merging or
     consolidating with, or by purchasing a substantial
     portion of the assets of, or by any other manner, any
     business or any corporation, limited liability company,
     partnership, joint venture, association or other
     business organization or division thereof, except for
     (x) such acquisitions which do not in the aggregate
     exceed $20,000,000 and (y) purchases of inventory,
     feedstock and other items in the ordinary course of
     business consistent with past practice;

          (v) sell, lease, license, mortgage or otherwise
     encumber or subject to any Lien or otherwise dispose of
     any of its properties or assets, other than (x) in the
     ordinary course of business consistent with past
     practice and (y) sales of assets which do not
     individually or in the aggregate exceed $20,000,000;

          (vi) (y) incur any indebtedness for borrowed money
     or guarantee any such indebtedness of another person,
     issue or sell any debt securities or warrants or other
     rights to acquire any debt securities of DSI or any of
     its subsidiaries, guarantee any debt securities of
     another person, enter into any "keep well" or other
     agreement to maintain any financial statement condition
     of another person or enter into any arrangement having
     the economic effect of any of the foregoing, except for
     short-term borrowings incurred in the ordinary course
     of business consistent with past practice, or (z) make
     any loans, advances or capital contributions to, or
     investments in, any other person, other than to DSI or
     any direct or indirect subsidiary of DSI or to officers
     and employees of DSI or any of its subsidiaries for
     travel, business or relocation expenses in the ordinary
     course of business;

          (vii) make or agree to make any capital expenditure
     or capital expenditures other than capital expenditures
     set forth in the operating budget of DSI previously


<PAGE>


     furnished to UC, the relevant portions of which are set
     forth in Section 4.01(b)(vii) of the DSI Disclosure
     Schedule;

          (viii) make any tax election that could reasonably
     be expected to have a material adverse effect on DSI or
     settle or compromise any material income tax liability;

          (ix) pay, discharge, settle or satisfy any material
     claims, liabilities or obligations (absolute, accrued,
     asserted or unasserted, contingent or otherwise), other
     than the payment, discharge, settlement or satisfaction,
     in the ordinary course of business consistent with past
     practice or in accordance with their terms, of
     liabilities reflected or reserved against in, or
     contemplated by, the most recent consolidated financial
     statements (or the notes thereto) of DSI included in the
     DSI Filed SEC Documents, incurred since the date of such
     financial statements in the ordinary course of business
     consistent with past practice or which do not in the
     aggregate have a material adverse effect on DSI;

          (x) except in the ordinary course of business or
     except as would not reasonably be expected to have a
     material adverse effect on DSI, modify, amend or
     terminate any material contract or agreement to which
     DSI or any subsidiary is a party or waive, release or
     assign any material rights or claims thereunder;

          (xi) make any material change to its accounting
     methods, principles or practices, except as may be
     required by generally accepted accounting principles;

          (xii) except as required by law or contemplated
     hereby, enter into, adopt or amend in any material
     respect or terminate any DSI Benefit Plan or any other
     agreement, plan or policy involving DSI or its
     subsidiaries and one or more of their directors,
     officers or employees, or materially change any
     actuarial or other assumption used to calculate funding
     obligations with respect to any DSI pension plans, or
     change the manner in which contributions to any DSI
     pension plans are made or the basis on which such
     contributions are determined;

          (xiii) except for normal increases in the ordinary
     course of business consistent with past practice that,


<PAGE>


     in the aggregate, do not materially increase benefits or
     compensation expenses of DSI or its subsidiaries, or as
     contemplated hereby or by the terms of any contract the
     existence of which does not constitute a violation of
     this Agreement, increase the compensation of any
     director, executive officer or other key employee of DSI
     or pay any benefit or amount not required by a plan or
     arrangement as in effect on the date of this Agreement
     to any such person; or

          (xiv) authorize, or commit or agree to take, any of
     the foregoing actions.

          (b) Conduct of Business by UC. Except as set forth
in Section 4.01 of the UC Disclosure Schedule, during the
period from the date of this Agreement to the Effective Time,
UC shall, and shall cause its subsidiaries to, carry on their
respective businesses in the usual, regular and ordinary
course in substantially the same manner as heretofore
conducted and in compliance in all material respects with all
applicable laws and regulations and, to the extent consistent
therewith, use all reasonable efforts to preserve intact
their current business organizations, use reasonable efforts
to keep available the services of their current officers and
other key employees and preserve their relationships with
those persons having business dealings with them to the end
that their goodwill and ongoing businesses shall be
unimpaired at the Effective Time. Except as set forth in
Section 4.01 of the UC Disclosure Schedule, without limiting
the generality of the foregoing, during the period from the
date of this Agreement to the Effective Time, UC shall not,
and shall not permit any of its subsidiaries to:

          (i) other than dividends and distributions
     (including liquidating distributions) by a direct or
     indirect wholly owned subsidiary of UC to its parent, or
     by a subsidiary that is partially owned by UC or any of
     its subsidiaries, provided that UC or any such
     subsidiary receives or is to receive its proportionate
     share thereof, and other than the regular quarterly
     dividends of $.275 per share with respect to the UC
     Common Stock, (x) declare, set aside or pay any
     dividends on, or make any other distributions in respect
     of, any of its capital stock, (y) split, combine or
     reclassify any of its capital stock or issue or
     authorize the issuance of any other securities in
     respect of, in lieu of or in substitution for shares of


<PAGE>


     its capital stock, or (z) purchase, redeem or otherwise
     acquire any shares of capital stock of UC or any of its
     Significant Subsidiaries or any other securities thereof
     or any rights, warrants or options to acquire any such
     shares or other securities;

          (ii) issue, deliver, sell, pledge or otherwise
     encumber any shares of its capital stock, any other
     voting securities or any securities convertible into, or
     any rights, warrants or options to acquire, any such
     shares, voting securities or convertible securities
     (other than (x) the issuance of UC Common Stock upon the
     exercise of UC Employee Stock Options outstanding on the
     date of this Agreement and in accordance with their
     present terms, and (y) the issuance of UC Common Stock
     pursuant to the UC Stock Option Agreement);

          (iii) except as contemplated hereby, amend its
     certificate of incorporation, by-laws or other
     comparable organizational documents;

          (iv) acquire or agree to acquire by merging or
     consolidating with, or by purchasing a substantial
     portion of the assets of, or by any other manner, any
     business or any corporation, limited liability company,
     partnership, joint venture, association or other
     business organization or division thereof, except for
     (x) such acquisitions which do not in the aggregate
     exceed $20,000,000 and (y) purchases of inventory,
     feedstock and other items in the ordinary course of
     business consistent with past practice;

          (v) sell, lease, license, mortgage or otherwise
     encumber or subject to any Lien or otherwise dispose of
     any of its properties or assets, other than (x) in the
     ordinary course of business consistent with past
     practice and (y) sales of assets which do not
     individually or in the aggregate exceed $20,000,000;

          (vi) (y) incur any indebtedness for borrowed money
     or guarantee any such indebtedness of another person,
     issue or sell any debt securities or warrants or other
     rights to acquire any debt securities of UC or any of
     its subsidiaries, guarantee any debt securities of
     another person, enter into any "keep well" or other
     agreement to maintain any financial statement condition
     of another person or enter into any arrangement having
     the economic effect of any of the foregoing, except for


<PAGE>


     short-term borrowings incurred in the ordinary course of
     business consistent with past practice, or (z) make any
     loans, advances or capital contributions to, or
     investments in, any other person, other than to UC or
     any direct or indirect subsidiary of UC or to officers
     and employees of UC or any of its subsidiaries for
     travel, business or relocation expenses in the ordinary
     course of business;

          (vii) make or agree to make any capital expenditure
     or capital expenditures other than capital expenditures
     set forth in the operating budget of UC previously
     furnished to DSI, the relevant portions of which are set
     forth in Section 4.01(b)(vii) of the UC Disclosure
     Schedule;

          (viii) make any tax election that could reasonably
     be expected to have a material adverse effect on UC or
     settle or compromise any material income tax liability;

          (ix) pay, discharge, settle or satisfy any material
     claims, liabilities or obligations (absolute, accrued,
     asserted or unasserted, contingent or otherwise), other
     than the payment, discharge, settlement or satisfaction,
     in the ordinary course of business consistent with past
     practice or in accordance with their terms, of
     liabilities reflected or reserved against in, or
     contemplated by, the most recent consolidated financial
     statements (or the notes thereto) of UC included in the
     UC Filed SEC Documents, incurred since the date of such
     financial statements in the ordinary course of business
     consistent with past practice or which do not in the
     aggregate have a material adverse effect on UC;

          (x) except in the ordinary course of business or
     except as would not reasonably be expected to have a
     material adverse effect on UC, modify, amend or
     terminate any material contract or agreement to which
     UC, any subsidiary is a party or waive, release or
     assign any material rights or claims thereunder;

          (xi) make any material change to its accounting
     methods, principles or practices, except as may be
     required by generally accepted accounting principles;

          (xii) except as required by law or contemplated
     hereby, enter into, adopt or amend in any material


<PAGE>


     respect or terminate any UC Benefit Plan or any other
     agreement, plan or policy involving UC or its
     subsidiaries and one or more of their directors,
     officers or employees, or materially change any
     actuarial or other assumption used to calculate funding
     obligations with respect to any UC pension plans, or
     change the manner in which contributions to any UC
     pension plans are made or the basis on which such
     contributions are determined;

          (xiii) except for normal increases in the ordinary
     course of business consistent with past practice that,
     in the aggregate, do not materially increase benefits or
     compensation expenses of UC or its subsidiaries, or as
     contemplated hereby or by the terms of any contract the
     existence of which does not constitute a violation of
     this Agreement, increase the compensation of any
     director, executive officer or other key employee of UC
     or pay any benefit or amount not required by a plan or
     arrangement as in effect on the date of this Agreement
     to any such person; or

          (xiv) authorize, or commit or agree to take, any of
     the foregoing actions.

          (c) Coordination of Dividends. Each of UC and DSI
shall coordinate with the other regarding the declaration and
payment of dividends in respect of the UC Common Stock and
the DSI Common Stock and the record dates and payment dates
relating thereto, it being the intention of UC and DSI that
any holder of DSI Common Stock shall not receive two
dividends, or fail to receive one dividend, for any single
calendar quarter with respect to its shares of DSI Common
Stock and/or any shares of UC Common Stock any such holder
receives in exchange therefor pursuant to the Merger.

          (d) Other Actions. Except as required by law, DSI
and UC shall not, and shall not permit any of their
respective subsidiaries to, voluntarily take any action that
would, or that could reasonably be expected to, result in (i)
any of the representations and warranties of such party set
forth in this Agreement or the Option Agreements that are
qualified as to materiality becoming untrue, (ii) any of such
representations and warranties that are not so qualified
becoming untrue in any material respect, or (iii) any of the
conditions to the Merger set forth in Article VI not being
satisfied.


<PAGE>


          (e) Advice of Changes. DSI and UC shall promptly
advise the other party orally and in writing of (i) any
representation or warranty made by it contained in this
Agreement or the Option Agreements that is qualified as to
materiality becoming untrue or inaccurate in any respect or
any such representation or warranty that is not so qualified
becoming untrue or inaccurate in any material respect, (ii)
the failure by it to comply in any material respect with or
satisfy in any material respect any covenant, condition or
agreement to be complied with or satisfied by it under this
Agreement or the Option Agreements, or (iii) any change or
event having, or which, insofar as can reasonably be
foreseen, could reasonably be expected to have, a material
adverse effect on such party or on the truth of their
respective representations and warranties or the ability of
the conditions set forth in Article VI to be satisfied;
provided, however, that no such notification shall affect the
representations, warranties, covenants or agreements of the
parties or the conditions to the obligations of the parties
under this Agreement or the Option Agreements.

          SECTION 4.02. No Solicitation by DSI. (a) DSI 
shall not, nor shall it permit any of its subsidiaries to,
nor shall it authorize or permit any of its officers,
directors or employees or any investment banker, financial
advisor, attorney, accountant or other representative
retained by it or any of its subsidiaries to, directly or
indirectly through another person, (i) solicit, initiate or
encourage (including by way of furnishing information), or
take any other action designed to facilitate, any inquiries
or the making of any proposal which constitutes any DSI
Takeover Proposal (as hereinafter defined) or 
(ii) participate in any discussions or negotiations
regarding any DSI Takeover Proposal; provided, however, that
if, at any time prior to the adoption of this Agreement by
the holders of DSI Common Stock, the Board of Directors of
DSI determines in good faith, after consultation with
outside counsel, that it is necessary to do so in order to
comply with its fiduciary duties to DSI's stockholders under
applicable law, DSI may, in response to a DSI Takeover
Proposal which was not solicited by it or which did not
otherwise result from a breach of this Section 4.02(a), and
subject to compliance with Section 4.02(c), (x) furnish
information with respect to DSI and its subsidiaries to any
person pursuant to a customary confidentiality agreement (as
determined by DSI after consultation with its outside
counsel) and (y) participate in negotiations regarding such


<PAGE>


DSI Takeover Proposal. For purposes of this Agreement, "DSI
Takeover Proposal" means any inquiry, proposal or offer from
any person relating to any direct or indirect acquisition or
purchase of 20% or more of the assets of DSI and its
subsidiaries or 20% or more of any class of equity
securities of DSI or any of its subsidiaries, any tender
offer or exchange offer that if consummated would result in
any person beneficially owning 20% or more of any class of
equity securities of DSI or any of its subsidiaries, or any
merger, consolidation, business combination,
recapitalization, liquidation, dissolution or similar
transaction involving DSI or any of its subsidiaries, other
than the transactions contemplated by this Agreement.

          (b) Except as expressly permitted by this Section
4.02, neither the Board of Directors of DSI nor any
committee thereof shall (i) withdraw or modify, or propose
publicly to withdraw or modify, in a manner adverse to UC,
the approval or recommendation by such Board of Directors or
such committee of the Merger or this Agreement, (ii) approve
or recommend, or propose publicly to approve or recommend,
any DSI Takeover Proposal, or (iii) cause DSI to enter into
any letter of intent, agreement in principle, acquisition
agreement or other similar agreement (each, a "DSI
Acquisition Agreement") related to any DSI Takeover
Proposal. Notwithstanding the foregoing, in the event that
prior to the adoption of this Agreement by the holders of
DSI Common Stock (x) the Board of Directors of DSI
determines in good faith, after it has received a DSI
Superior Proposal (as defined below) and after consultation
with outside counsel, that it is necessary to do so in order
to comply with its fiduciary duties to DSI's stockholders
under applicable law, the Board of Directors of DSI may
(subject to this and the following sentences) withdraw or
modify its approval or recommendation of the Merger or this
Agreement, or (y) the Board of Directors of DSI determines
in good faith that there is not a substantial probability
that the adoption of this Agreement by holders of DSI Common
Stock will be obtained due to the existence of a DSI
Superior Proposal, the Board of Directors of DSI may
(subject to this and the following sentences) approve or
recommend such DSI Superior Proposal or terminate this
Agreement (and concurrently with or after such termination,
if it so chooses, cause DSI to enter into any DSI
Acquisition Agreement with respect to any DSI Superior
Proposal), but in each of the cases set forth in this 
clause (y), only at a time that is after the fifth business
day following UC's receipt of written notice advising UC


<PAGE>

that the Board of Directors of DSI has received a DSI
Superior Proposal, specifying the material terms and
conditions of such DSI Superior Proposal and identifying the
person making such DSI Superior Proposal. For purposes of
this Agreement, a "DSI Superior Proposal" means any proposal
made by a third party to acquire, directly or indirectly,
for consideration consisting of cash and/or securities, more
than 50% of the combined voting power of the shares of DSI
Common Stock then outstanding or all or substantially all
the assets of DSI and otherwise on terms which the Board of
Directors of DSI determines in its good faith judgment
(based on the advice of a financial advisor of nationally
recognized reputation) to be more favorable to DSI's
stockholders than the Merger and for which financing, to the
extent required, is then committed or which, in the good
faith judgment of the Board of Directors of DSI, is
reasonably capable of being obtained by such third party.

          (c) In addition to the obligations of DSI set
forth in paragraphs (a) and (b) of this Section 4.02, DSI
shall immediately advise UC orally and in writing of any
request for information or of any DSI Takeover Proposal, the
material terms and conditions of such request or DSI
Takeover Proposal and the identity of the person making such
request or DSI Takeover Proposal. DSI will keep UC
reasonably informed of the status and details (including
amendments or proposed amendments) of any such request or
DSI Takeover Proposal.

          (d) Nothing contained in this Section 4.02 shall
prohibit DSI from taking and disclosing to its stockholders
a position contemplated by Rule 14e-2(a) promulgated under
the Exchange Act or from making any disclosure to DSI's
stockholders if, in the good faith judgment of the Board of
Directors of DSI, after consultation with outside counsel,
failure so to disclose would be inconsistent with its
fiduciary duties to DSI's stockholders under applicable law;
provided, however, that neither DSI nor its Board of
Directors nor any committee thereof shall, except as
permitted by Section 4.02(b), withdraw or modify, or propose
publicly to withdraw or modify, its position with respect to
this Agreement or the Merger or approve or recommend, or
propose publicly to approve or recommend, a DSI Takeover
Proposal.

          SECTION 4.03. No Solicitation by UC. (a) UC 
shall not, nor shall it permit any of its subsidiaries to,
nor shall it authorize or permit any of its officers,


<PAGE>


directors or employees or any investment banker, financial
advisor, attorney, accountant or other representative
retained by it or any of its subsidiaries to, directly or
indirectly through another person, (i) solicit, initiate or
encourage (including by way of furnishing information), or
take any other action designed to facilitate, any inquiries
or the making of any proposal which constitutes any UC
Takeover Proposal (as hereinafter defined) or (ii)
participate in any discussions or negotiations regarding any
UC Takeover Proposal; provided, however, that if, at any
time prior to the adoption of this Agreement by the holders
of UC Common Stock, the Board of Directors of UC determines
in good faith, after consultation with outside counsel, that
it is necessary to do so in order to comply with its
fiduciary duties to UC's stockholders under applicable law,
UC may, in response to a UC Takeover Proposal which was not
solicited by it or which did not otherwise result from a
breach of this Section 4.03(a), and subject to compliance
with Section 4.03(c), (x) furnish information with respect
to UC and its subsidiaries to any person pursuant to a
customary confidentiality agreement (as determined by UC
after consultation with its outside counsel) and (y)
participate in negotiations regarding such UC Takeover
Proposal. For purposes of this Agreement, "UC Takeover
Proposal" means any inquiry, proposal or offer from any
person relating to any direct or indirect acquisition or
purchase of 20% or more of the assets of UC and its
subsidiaries or 20% or more of any class of equity
securities of UC or any of its subsidiaries, any tender
offer or exchange offer that if consummated would result in
any person beneficially owning 20% or more of any class of
equity securities of UC or any of its subsidiaries, or any
merger, consolidation, business combination,
recapitalization, liquidation, dissolution or similar
transaction involving UC or any of its subsidiaries, other
than the transactions contemplated by this Agreement.

          (b) Except as expressly permitted by this Section
4.03, neither the Board of Directors of UC nor any committee
thereof shall (i) withdraw or modify, or propose publicly to
withdraw or modify, in a manner adverse to DSI, the approval
or recommendation by such Board of Directors or such
committee of the Merger, this Agreement or the issuance of
UC Common Stock and UC Convertible Preferred Stock in
connection with the Merger, (ii) approve or recommend, or
propose publicly to approve or recommend, any UC Takeover
Proposal, or (iii) cause UC to enter into any letter of
intent, agreement in principle, acquisition agreement or


<PAGE>


other similar agreement (each, a "UC Acquisition Agreement")
related to any UC Takeover Proposal. Notwithstanding the
foregoing, in the event that prior to the adoption of this
Agreement by the holders of UC Common Stock (x) the Board of
Directors of UC determines in good faith, after it has
received a UC Superior Proposal (as defined below) and after
consultation with outside counsel, that it is necessary to
do so in order to comply with its fiduciary duties to UC's
stockholders under applicable law, the Board of Directors of
UC may (subject to this and the following sentences)
withdraw or modify its approval or recommendation of the
Merger, this Agreement or the issuance of UC Common Stock in
connection with the Merger, or (y) the Board of Directors of
UC determines in good faith that there is not a substantial
probability that the adoption of this Agreement by holders
of UC Common Stock will be obtained due to the existence of
a UC Superior Proposal, the Board of Directors of UC may
(subject to this and the following sentences) approve or
recommend such UC Superior Proposal or terminate this
Agreement (and concurrently with or after such termination,
if it so chooses, cause UC to enter into any UC Acquisition
Agreement with respect to any UC Superior Proposal), but in
each of the cases set forth in this clause (y), only at a
time that is after the fifth business day following DSI's
receipt of written notice advising DSI that the Board of
Directors of UC has received a UC Superior Proposal,
specifying the material terms and conditions of such UC
Superior Proposal and identifying the person making such UC
Superior Proposal. For purposes of this Agreement, a "UC
Superior Proposal" means any proposal made by a third party
to acquire, directly or indirectly, for consideration
consisting of cash and/or securities, more than 50% of the
combined voting power of the shares of UC Common Stock then
outstanding or all or substantially all the assets of UC and
otherwise on terms which the Board of Directors of UC
determines in its good faith judgment (based on the advice
of a financial advisor of nationally recognized reputation)
to be more favorable to UC's stockholders than the Merger
and for which financing, to the extent required, is then
committed or which, in the good faith judgment of the Board
of Directors of UC, is reasonably capable of being obtained
by such third party.

          (c) In addition to the obligations of UC set 
forth in paragraphs (a) and (b) of this Section 4.03, UC
shall immediately advise DSI orally and in writing of any
request for information or of any UC Takeover Proposal, the
material terms and conditions of such request or UC Takeover


<PAGE>


Proposal and the identity of the person making such request
or UC Takeover Proposal. UC will keep DSI reasonably
informed of the status and details (including amendments or
proposed amendments) of any such request or UC Takeover
Proposal.

          (d) Nothing contained in this Section 4.03 shall
prohibit UC from taking and disclosing to its stockholders a
position contemplated by Rule 14e-2(a) promulgated under the
Exchange Act or from making any disclosure to UC's
stockholders if, in the good faith judgment of the Board of
Directors of UC, after consultation with outside counsel,
failure so to disclose would be inconsistent with its
fiduciary duties to UC's stockholders under applicable law;
provided, however, that neither UC nor its Board of
Directors nor any committee thereof shall, except as
permitted by Section 4.03(b), withdraw or modify, or propose
publicly to withdraw or modify, its position with respect to
this Agreement, the Merger, the issuance of UC Common Stock
and UC Convertible Preferred Stock in connection with the
Merger, or approve or recommend, or propose publicly to
approve or recommend, a UC Takeover Proposal.


                          ARTICLE V

                    Additional Agreements

          SECTION 5.01. Preparation of the Form S-4 and the
Joint Proxy Statement; Stockholders Meetings. (a) As soon as
practicable following the date of this Agreement, DSI and UC
shall prepare and file with the SEC the Joint Proxy
Statement and UC shall prepare and file with the SEC the
Form S-4, in which the Joint Proxy Statement will be
included as a prospectus. Each of DSI and UC shall use all
reasonable efforts to have the Form S-4 declared effective
under the Securities Act as promptly as practicable after
such filing. DSI will use all reasonable efforts to cause
the Joint Proxy Statement to be mailed to DSI's
stockholders, and UC will use all reasonable efforts to
cause the Joint Proxy Statement to be mailed to UC's
stockholders, in each case as promptly as practicable after
the Form S-4 is declared effective under the Securities Act.
UC shall also take any action (other than qualifying to do
business in any jurisdiction in which it is not now so
qualified or to file a general consent to service of
process) required to be taken under any applicable state
securities laws in connection with the issuance of UC Common


<PAGE>


Stock and UC Convertible Preferred Stock in the Merger and
under the DSI Stock Plans and UC Stock Plans and DSI shall
furnish all information concerning DSI and the holders of
DSI Common Stock as may be reasonably requested in
connection with any such action.

          (b) DSI will, as soon as practicable following the
date of this Agreement, duly call, give notice of, convene
and hold a meeting of its stockholders (the "DSI
Stockholders Meeting") for the purpose of obtaining the DSI
Stockholder Approval. Without limiting the generality of the
foregoing but subject to Section 4.02(b), DSI agrees that
its obligations pursuant to the first sentence of this
Section 5.01(b) shall not be affected by the commencement,
public proposal, public disclosure or communication to DSI
of any DSI Takeover Proposal. DSI will, through its Board of
Directors, recommend to its stockholders the approval and
adoption of this Agreement, the Merger and the other
transactions contemplated hereby, except to the extent that
the Board of Directors of DSI shall have withdrawn or
modified its approval or recommendation of this Agreement or
the Merger and terminated this Agreement in accordance with
Section 4.02(b).

          (c) UC will, as soon as practicable following the
date of this Agreement, duly call, give notice of, convene
and hold a meeting of its stockholders (the "UC Stockholders
Meeting") for the purpose of obtaining the UC Stockholder
Approval. Without limiting the generality of the foregoing
but subject to Section 4.03(b), UC agrees that its
obligations pursuant to the first sentence of this Section
5.01(c) shall not be affected by the commencement, public
proposal, public disclosure or commencement to UC of any UC
Takeover Proposal. UC will, through its Board of Directors,
recommend to its stockholders the approval and adoption of
this Agreement, the Merger and the other transactions
contemplated hereby, including the issuance of UC Common
Stock pursuant to the Merger, except to the extent that the
Board of Directors of UC shall have withdrawn or modified
its recommendation and terminated this Agreement in
accordance with Section 4.03(b).

          (d) UC and DSI will use reasonable efforts to hold
the DSI Stockholders Meeting and the UC Stockholders Meeting
on the same date and as soon as practicable after the date
hereof.


<PAGE>


          SECTION 5.02. Letters of DSI's Accountants. (a)
DSI shall use reasonable efforts to cause to be delivered to
UC two letters from Price Waterhouse LLP, DSI's independent
accountants, one dated a date within two business days
before the date on which the Form S-4 shall become effective
and one dated a date within two business days before the
Closing Date, each addressed to UC, in form and substance
reasonably satisfactory to UC and customary in scope and
substance for comfort letters delivered by independent
public accountants in connection with registration
statements similar to the Form S-4.

          (b) DSI shall use its reasonable efforts to cause
to be delivered to UC a letter from Price Waterhouse LLP
addressed to UC and DSI, dated as of the Closing Date,
stating that the Merger will qualify as a pooling of
interests transaction under Opinion 16 of the Accounting
Principles Board and applicable SEC rules and regulations.

          SECTION 5.03. Letters of UC's Accountants. (a) UC
shall use reasonable efforts to cause to be delivered to DSI
two letters from Ernst & Young LLP, UC's independent
accountants, one dated a date within two business days
before the date on which the Form S-4 shall become effective
and one dated a date within two business days before the
Closing Date, each addressed to DSI, in form and substance
reasonably satisfactory to DSI and customary in scope and
substance for comfort letters delivered by independent
public accountants in connection with registration
statements similar to the Form S-4.

          (b) UC shall use its reasonable efforts to cause
to be delivered to DSI a letter from Ernst & Young LLP,
addressed to DSI and UC, dated as of the Closing Date,
stating that the Merger will qualify as a pooling of
interests transaction under Opinion 16 of the Accounting
Principles Board and applicable SEC rules and regulations.

          SECTION 5.04. Access to Information;
Confidentiality. Subject to the Confidentiality Agreement
(as defined below), each of DSI and UC shall, and shall
cause each of its respective subsidiaries to, afford to the
other party and to the officers, employees, accountants,
counsel, financial advisors and other representatives of
such other party, reasonable access during normal business
hours during the period prior to the Effective Time to all
their respective properties, books, contracts, commitments,
personnel and records and, during such period, each of DSI


<PAGE>


and UC shall, and shall cause each of its respective
subsidiaries to, furnish promptly to the other party (a) a
copy of each report, schedule, registration statement and
other document filed by it during such period pursuant to
the requirements of federal or state securities laws and (b)
all other information concerning its business, properties
and personnel as such other party may reasonably request.
Each of DSI and UC will hold, and will cause its respective
officers, employees, accountants, counsel, financial
advisors and other representatives and affiliates to hold,
any nonpublic information in accordance with the terms of
the Confidentiality Agreement dated April 27, 1994, as
amended as of September 3, 1996, between UC and DSI (as
amended pursuant to the following sentence, the
"Confidentiality Agreement"). UC and DSI agree that the
Confidentiality Agreement is hereby amended to delete
paragraph 5 thereof.

          SECTION 5.05. Reasonable Efforts. (a) Upon the
terms and subject to the conditions set forth in this
Agreement, each of the parties agrees to use all reasonable
efforts to take, or cause to be taken, all actions, and to
do, or cause to be done, and to assist and cooperate with
the other parties in doing, all things necessary, proper or
advisable to consummate and make effective, in the most
expeditious manner practicable, the Merger and the other
transactions contemplated by this Agreement and the Option
Agreements, including (i) the obtaining of all necessary
actions or nonactions, waivers, consents and approvals from
Governmental Entities and the making of all necessary
registrations and filings (including filings with
Governmental Entities, such as those referred to in 
Sections 3.01(d)(1)-(5) and 3.02(d)(1)-(5)) and the taking
of all reasonable steps as may be necessary to obtain an
approval or waiver from, or to avoid an action or proceeding
by, any Governmental Entity, (ii) the obtaining of all
necessary consents, approvals or waivers from third parties,
(iii) the defending of any lawsuits or other legal
proceedings, whether judicial or administrative, challenging
this Agreement or the Option Agreements or the consummation
of the transactions contemplated by this Agreement or the
Option Agreements, including seeking to have any stay or
temporary restraining order entered by any court or other
Governmental Entity vacated or reversed, and (iv) the
execution and delivery of any additional instruments
necessary to consummate the transactions contemplated by,
and to fully carry out the purposes of, this Agreement and
the Option Agreements. Nothing set forth in this 


<PAGE>


Section 5.05(a) will limit or affect actions permitted to be
taken pursuant to Sections 4.02 and 4.03.

          (b) In connection with and without limiting the
foregoing, DSI and UC shall (i) take all action necessary to
ensure that no state takeover statute or similar statute or
regulation is or becomes applicable to the Merger, this
Agreement, the Option Agreements or any of the other
transactions contemplated by this Agreement or the Option
Agreements and (ii) if any state takeover statute or similar
statute or regulation becomes applicable to the Merger, this
Agreement, the Option Agreements or any other transaction
contemplated by this Agreement or the Option Agreements,
take all action necessary to ensure that the Merger and the
other transactions contemplated by this Agreement and the
Option Agreements may be consummated as promptly as
practicable on the terms contemplated by this Agreement and
the Option Agreements and otherwise to minimize the effect
of such statute or regulation on the Merger and the other
transactions contemplated by this Agreement and the Option
Agreements.

          SECTION 5.06. Stock Options. (a) As soon as
practicable following the date of this Agreement, the Board
of Directors of DSI (or, if appropriate, any committee
administering the DSI Stock Plans) shall adopt such
resolutions or take such other actions as may be required to
effect the following:

          (i) adjust the terms of all outstanding DSI
     Employee Stock Options granted under DSI Stock Plans,
     whether vested or unvested, as necessary to provide
     that, at the Effective Time, each DSI Employee Stock
     Option outstanding immediately prior to the Effective
     Time shall be deemed to constitute an option to
     acquire, on the same terms and conditions as were
     applicable under such DSI Employee Stock Option,
     including vesting, the same number of shares of UC
     Common Stock as the holder of such DSI Employee Stock
     Option would have been entitled to receive pursuant to
     the Merger had such holder exercised such DSI Employee
     Stock Option in full immediately prior to the Effective
     Time, at a price per share of UC Common Stock equal to
     (A) the aggregate exercise price for the shares of DSI
     Common Stock otherwise purchasable pursuant to such DSI
     Employee Stock Option divided by (B) the aggregate
     number of shares of UC Common Stock deemed purchasable
     pursuant to such DSI Employee Stock Option (each, as so


<PAGE>


     adjusted, an "Adjusted Option"); provided, however,
     that in the case of any option to which Section 421 of
     the Code applies by reason of its qualification under
     any of Sections 422 through 424 of the Code ("qualified
     stock options"), the option price, the number of shares
     purchasable pursuant to such option and the terms and
     conditions of exercise of such option shall be
     determined in order to comply with Section 424 of the
     Code; and

          (ii) make such other changes to the DSI Stock
     Plans as DSI and UC may agree are appropriate to give
     effect to the Merger.

          (b) As soon as practicable after the Effective
Time, UC shall deliver to the holders of DSI Employee Stock
Options appropriate notices setting forth such holders'
rights pursuant to the respective DSI Stock Plans and the
agreements evidencing the grants of such DSI Employee Stock
Options and that such DSI Employee Stock Options and
agreements shall be assumed by UC and shall continue in
effect on the same terms and conditions (subject to the
adjustments required by this Section 5.06 after giving
effect to the Merger). UC shall comply with the terms of the
DSI Stock Plans and ensure, to the extent required by, and
subject to the provisions of, such DSI Stock Plans, that the
DSI Employee Stock Options which qualified as qualified
stock options prior to the Effective Time continue to
qualify as qualified stock options after the Effective Time.

          (c) UC shall take such actions as are reasonably
necessary for the assumption of the DSI Stock Plans pursuant
to Section 5.06(a), including the reservation, issuance and
listing of UC Common Stock as is necessary to effectuate the
transactions contemplated by Section 5.06(a). As soon as
reasonably practicable after the Effective Time, UC shall
prepare and file with the SEC a registration statement on
Form S-8 or other appropriate form with respect to shares of
UC Common Stock subject to DSI Employee Stock Options issued
under such DSI Stock Plans and shall use all reasonable
efforts to maintain the effectiveness of a registration
statement or registration statements covering such DSI
Employee Stock Options (and maintain the current status of
the prospectus or prospectuses contained therein) for so
long as such DSI Employee Stock Options remain outstanding.
With respect to those individuals, if any, who subsequent to
the Effective Time will be subject to the reporting
requirements under Section 16(a) of the Exchange Act, where


<PAGE>


applicable, UC shall use all reasonable efforts to
administer the DSI Stock Plans assumed pursuant to Section
5.06(b) in a manner that complies with Rule 16b-3
promulgated under the Exchange Act to the extent the
applicable DSI Stock Plan complied with such rule prior to
the Merger.

          (d) A holder of an Adjusted Option may exercise
such Adjusted Option in whole or in part in accordance with
its terms by delivering a properly executed notice of
exercise to UC, together with the consideration therefor and
the federal withholding tax information, if any, required in
accordance with the related DSI Stock Plan.

          (e) Except as otherwise contemplated by this
Section 5.06, all restrictions or limitations on transfer
and vesting with respect to DSI Employee Stock Options
awarded under the DSI Stock Plans or any other plan, program
or arrangement of DSI or any of its subsidiaries, to the
extent that such restrictions or limitations shall not have
already lapsed, shall remain in full force and effect with
respect to such options after giving effect to the Merger
and the assumption by UC as set forth above.

          SECTION 5.07. Certain Employee Matters. Each of
DSI and UC will take the actions indicated to be taken by it
in Schedule 5.07 at or prior to the times specified therein.
Following the Effective Time, UC, as the Surviving
Corporation in the Merger, will honor all obligations under
employment agreements of DSI or UC the existence of which
does not constitute a violation of this Agreement in
accordance with the terms thereof.

          SECTION 5.08. Indemnification, Exculpation and
Insurance. (a) UC agrees that all rights to 
indemnification and exculpation from liabilities for acts or
omissions occurring at or prior to the Effective Time now
existing in favor of the current or former directors or
officers of DSI and its subsidiaries as provided in their
respective certificates of incorporation or by-laws (or
comparable organizational documents) and any indemnification
agreements of DSI, the existence of which does not
constitute a breach of this Agreement, shall be assumed by
UC, as the Surviving Corporation in the Merger, without
further action, as of the Effective Time and shall survive
the Merger and shall continue in full force and effect in
accordance with their terms. In addition, from and after 
the Effective Time, directors and officers of DSI who become


<PAGE>


directors or officers of UC will be entitled to the same
indemnity rights and protections as are afforded to other
directors and officers of UC.

          (b) In the event that UC or any of its successors
or assigns (i) consolidates with or merges into any other
person and is not the continuing or surviving corporation or
entity of such consolidation or merger or (ii) transfers or
conveys all or substantially all of its properties and
assets to any person, then, and in each such case, proper
provision will be made so that the successors and assigns of
UC assume the obligations set forth in this Section.

          (c) The provisions of this Section 5.08 (i) are
intended to be for the benefit of, and will be enforceable
by, each indemnified party, his or her heirs and his or her
representatives and (ii) are in addition to, and not in
substitution for, any other rights to indemnification or
contribution that any such person may have by contract or
otherwise.

          SECTION 5.09. Fees and Expenses. (a) Except as set
forth in this Section 5.09, all fees and expenses incurred
in connection with the Merger, this Agreement, the Option
Agreements and the transactions contemplated by this
Agreement and the Option Agreements shall be paid by the
party incurring such fees or expenses, whether or not the
Merger is consummated, except that each of UC and DSI shall
bear and pay one-half of the costs and expenses incurred in
connection with (i) the filing, printing and mailing of the
Form S-4 and the Joint Proxy Statement (including SEC filing
fees) and (ii) the filings of the premerger notification and
report forms under the HSR Act (including filing fees).

          (b) In the event that (i) a DSI Takeover Proposal
shall have been made known to DSI or any of its subsidiaries
or has been made directly to its stockholders generally or
any person shall have publicly announced an intention
(whether or not conditional) to make a DSI Takeover Proposal
and thereafter this Agreement is terminated by either UC or
DSI pursuant to Section 7.01(b)(i) or (ii), or (ii) this
Agreement is terminated (x) by DSI pursuant to Section
7.01(h) or (y) by UC pursuant to Section 7.01(e) or (f),
then DSI shall promptly, but in no event later than two days
after the date of such termination, pay UC a fee equal to
$45 million (the "Termination Fee"), payable by wire
transfer of same day funds; provided, however, that no
Termination Fee shall be payable to UC pursuant to clause


<PAGE>


(i) of this paragraph (b) or pursuant to a termination by UC
pursuant to Section 7.01(e) or (f) unless and until within
18 months of such termination DSI or any of its subsidiaries
enters into any DSI Acquisition Agreement or consummates any
DSI Takeover Proposal (for the purposes of the foregoing
proviso the terms "DSI Acquisition Agreement" and "DSI
Takeover Proposal" shall have the meanings assigned to such
terms in Section 4.02 except that the references to "20%" in
the definition of "DSI Takeover Proposal" in Section 4.02(a)
shall be deemed to be references to "35%"). DSI acknowledges
that the agreements contained in this Section 5.09(b) are an
integral part of the transactions contemplated by this
Agreement, and that, without these agreements, UC would not
enter into this Agreement; accordingly, if DSI fails
promptly to pay the amount due pursuant to this Section
5.09(b), and, in order to obtain such payment, UC commences
a suit which results in a judgment against DSI for the fee
set forth in this Section 5.09(b), DSI shall pay to UC its
costs and expenses (including attorneys' fees and expenses)
in connection with such suit, together with interest on the
amount of the fee at the prime rate of Citibank N.A. in
effect on the date such payment was required to be made. In
the event of a termination by UC pursuant to Section 7.01(e)
or (f), DSI shall promptly pay upon UC's request all
out-of-pocket expenses incurred by UC in connection with
this Agreement, the Option Agreements and the transactions
contemplated hereby and thereby in an amount not to exceed
$5 million, which payments shall be credited against any
Termination Fee that may subsequently become payable.

          (c) In the event that (i) a UC Takeover Proposal
shall have been made known to UC or any of its subsidiaries
or has been made directly to its stockholders generally or
any person shall have publicly announced an intention
(whether or not conditional) to make a UC Takeover Proposal
and thereafter this Agreement is terminated by either UC or
DSI pursuant to Section 7.01(b)(i) or (iii), or (ii) this
Agreement is terminated (x) by UC pursuant to 
Section 7.01(d) or (y) by DSI pursuant to Section 7.01(i) or
(j), then UC shall promptly, but in no event later than two
days after the date of such termination, pay DSI the
Termination Fee, payable by wire transfer of same day funds;
provided, however, that no Termination Fee shall be payable
to DSI pursuant to clause (i) of this paragraph (c) or
pursuant to a termination by DSI pursuant to Section 7.01(i)
or (j) unless and until within 18 months of such termination
UC or any of its subsidiaries enters into any UC Acquisition


<PAGE>


Agreement or consummates any UC Takeover Proposal (for the
purposes of the foregoing proviso the terms "UC Acquisition
Agreement" and "UC Takeover Proposal" shall have the
meanings assigned to such terms in Section 4.03 except that
the references to "20%" in the definition of "UC Takeover
Proposal" in Section 4.03(a) shall be deemed to be
references to "35%"). UC acknowledges that the agreements
contained in this Section 5.09(c) are an integral part of
the transactions contemplated by this Agreement, and that,
without these agreements, DSI would not enter into this
Agreement; accordingly, if UC fails promptly to pay the
amount due pursuant to this Section 5.09(c), and, in order
to obtain such payment, DSI commences a suit which results
in a judgment against UC for the fee set forth in this
Section 5.09(c), UC shall pay to DSI its costs and expenses
(including attorneys' fees and expenses) in connection with
such suit, together with interest on the amount of the fee
at the prime rate of Citibank N.A. in effect on the date
such payment was required to be made. In the event of a
termination by DSI pursuant to Section 7.01(i) or (j), UC
shall promptly pay upon DSI's request all out-of-pocket
expenses incurred by DSI in connection with this Agreement,
the Option Agreements and the transactions contemplated
hereby and thereby in an amount not to exceed $5 million,
which payments shall be credited against any Termination Fee
that may subsequently become payable.

          SECTION 5.10. Public Announcements. UC and DSI
will consult with each other before issuing, and provide
each other the opportunity to review, comment upon and
concur with, any press release or other public statements
with respect to the transactions contemplated by this
Agreement, including the Merger, and the Option Agreements,
and shall not issue any such press release or make any such
public statement prior to such consultation, except as
either party may determine is required by applicable law,
court process or by obligations pursuant to any listing
agreement with any national securities exchange. The parties
agree that the initial press release to be issued with
respect to the transactions contemplated by this Agreement
and the Option Agreements shall be in the form heretofore
agreed to by the parties.

          SECTION 5.11. Affiliates. Prior to the Closing
Date, DSI shall deliver to UC a letter identifying all
persons who are, at the time this Agreement is submitted for
adoption by to the stockholders of DSI, "affiliates" of DSI
for purposes of Rule 145 under the Securities Act or for


<PAGE>


purposes of qualifying the Merger for pooling of interests
accounting treatment under Opinion 16 of the Accounting
Principles Board and applicable SEC rules and regulations.
DSI shall use all reasonable efforts to cause each such
person to deliver to UC on or prior to the Closing Date a
written agreement substantially in the form attached as
Exhibit C hereto. UC shall use reasonable efforts to cause
all persons who are "affiliates" of UC for purposes of
qualifying the Merger for pooling of interests accounting
treatment under Opinion 16 of the Accounting Principles
Board and applicable SEC rules and regulations to comply
with the fourth paragraph of Exhibit C hereto.

          SECTION 5.12. NYSE Listing. UC shall use
reasonable efforts to cause the shares of UC Common Stock to
be issued in the Merger, under the DSI Stock Plans and
pursuant to the UC Stock Option Agreement to be approved for
listing on the NYSE, subject to official notice of issuance,
prior to the Closing Date. DSI shall use reasonable efforts
to cause the shares of DSI Common Stock to be issued
pursuant to the DSI Stock Option Agreement to be approved
for listing on the NYSE, subject to official notice of
issuance, prior to the Closing Date.

          SECTION 5.13. Stockholder Litigation. Each of DSI
and UC shall give the other the reasonable opportunity to
participate in the defense of any stockholder litigation
against DSI or UC, as applicable, and its directors relating
to the transactions contemplated by this Agreement.

          SECTION 5.14. Tax Treatment. Each of UC and DSI
shall use reasonable efforts to cause the Merger to qualify
as a reorganization under the provisions of Section 368 of
the Code and to obtain the opinions of counsel referred to
in Sections 6.02 and 6.03.

          SECTION 5.15. Pooling of Interests. Each of DSI
and UC will use reasonable efforts to cause the transactions
contemplated by this Agreement, including the Merger, and
the Option Agreements to be accounted for as a pooling of
interests under Opinion 16 of the Accounting Principles
Board and applicable SEC rules and regulations, and such
accounting treatment to be accepted by each of DSI's and
UC's independent certified public accountants, and by the
SEC, respectively, and each of DSI and UC agrees that it
will voluntarily take no action that would cause such
accounting treatment not to be obtained.


<PAGE>


          SECTION 5.16. DSI Rights Agreement. The Board of
Directors of DSI shall take all further action (in addition
to that referred to in Section 3.01(s)) reasonably requested
in writing by UC (including redeeming the DSI Rights
immediately prior to the Effective Time or amending the DSI
Rights Agreement) in order to render the DSI Rights
inapplicable to the Merger and the other transactions
contemplated by this Agreement and the Option Agreements to
the extent provided herein and in the DSI Rights Plan
Amendment. Except as provided above with respect to the
Merger and the other transactions contemplated by this
Agreement and the Option Agreements, the Board of Directors
of DSI shall not (a) amend the DSI Rights Agreement or (b)
take any action with respect to, or make any determination
under, the DSI Rights Agreement, including a redemption of
the DSI Rights or any action to facilitate a DSI Takeover
Proposal.

          SECTION 5.17. UC Rights Agreement. The Board of
Directors of UC shall take all further action (in addition
to that referred to in Section 3.02(s)) reasonably requested
in writing by DSI (including redeeming the UC Rights
immediately prior to the Effective Time or amending the UC
Rights Agreement) in order to render the UC Rights
inapplicable to the Merger and the other transactions
contemplated by this Agreement and the Option Agreements to
the extent provided herein and in the UC Rights Plan
Amendment. Except as provided above with respect to the
Merger and the other transactions contemplated by this
Agreement and the Option Agreements, the Board of Directors
of UC shall not (a) amend the UC Rights Agreement or (b)
take any action with respect to, or make any determination
under, the UC Rights Agreement, including a redemption of
the UC Rights or any action to facilitate a UC Takeover
Proposal.

          SECTION 5.18. Headquarters. UC and DSI each agree
that following the consummation of the Merger the corporate
headquarters of UC shall be located in San Antonio, Texas,
and each agrees to take all necessary action to effect the
relocation of UC's corporate headquarters.

          SECTION 5.19. UC Convertible Preferred Stock.
Prior to the Effective Time, the Board of Directors of UC
will take all necessary action to establish the terms of the
UC Convertible Preferred Stock as contemplated by this
Agreement and file a certificate of designations (the
"Certificate of Designations") with respect to the UC


<PAGE>


Convertible Preferred Stock with the Delaware Secretary of
State, all in accordance with the applicable provisions of
the DGCL. The Certificate of Designations will in all
respects be identical to the existing certificate of
designations for the DSI Convertible Preferred Stock except
(a) as set forth in Section 2.01(c)(i), and (b) that the
Certificate of Designations will state that UC's obligations
to pay dividends will commence on March 15, June 15,
September 15 or December 15, whichever first occurs
following the Effective Time.

          SECTION 5.20. Indemnification Agreements. UC and
DSI agree that as soon as practicable after the Effective
Time the Surviving Corporation will enter into
indemnification agreements with the directors and officers
of the Surviving Corporation providing for indemnification
on the terms set forth in the by-laws of the Surviving
Corporation, as amended pursuant to Section 1.05.

          SECTION 5.21. Certain Tax Matters. UC and DSI
agree that they will not treat the Merger as a change in the
ownership or effective control of UC or a change in the
ownership of a substantial portion of the assets of UC, each
within the meaning of Section 280G of the Code, unless
otherwise required by a determination (as defined in Section
1313 of the Code).


                         ARTICLE VI

                    Conditions Precedent

          SECTION 6.01. Conditions to Each Party's
Obligation To Effect the Merger. The respective obligation
of each party to effect the Merger is subject to the
satisfaction or waiver on or prior to the Closing Date of
the following conditions:

          (a) Stockholder Approvals. Each of the DSI
     Stockholder Approval and the UC Stockholder Approval
     shall have been obtained.

          (b) HSR Act. The waiting period (and any extension
     thereof) applicable to the Merger under the HSR Act
     shall have been terminated or shall have expired.


<PAGE>


          (c) No Injunctions or Restraints. No judgment,
     order, decree, statute, law, ordinance, rule,
     regulation, temporary restraining order, preliminary or
     permanent injunction or other order enacted, entered,
     promulgated, enforced or issued by any court of
     competent jurisdiction or other Governmental Entity or
     other legal restraint or prohibition (collectively,
     "Restraints") preventing the consummation of the Merger
     shall be in effect; provided, however, that each of the
     parties shall have used reasonable efforts to prevent
     the entry of any such Restraints and to appeal as
     promptly as possible any such Restraints that may be
     entered.

          (d) No Litigation. There shall not be pending any
     suit, action or proceeding, in each case brought by any
     Governmental Entity and (i) seeking to restrain or
     prohibit the consummation of the Merger or any of the
     other transactions contemplated by this Agreement or
     the Option Agreements or seeking to obtain from either
     of DSI or UC any damages that are material in relation
     to DSI and its subsidiaries taken as a whole or UC and
     its subsidiaries taken as a whole, as applicable, (ii)
     seeking to prohibit or limit the ownership or operation
     by DSI, UC or any of their respective subsidiaries of
     any material portion of the business or assets of DSI,
     UC or any of their respective subsidiaries, or to
     compel DSI, UC or any of their respective subsidiaries
     to dispose of or hold separate any material portion of
     the business or assets of DSI, UC or any of their
     respective subsidiaries, as a result of the Merger or
     any of the other transactions contemplated by this
     Agreement or the Option Agreements or (iii) which
     otherwise could reasonably be expected to have a
     material adverse effect on DSI or UC, as applicable. In
     addition, there shall not be any Restraint enacted,
     entered, enforced or promulgated that is reasonably
     likely to result, directly or indirectly, in any of the
     consequences referred to in clauses (ii) or (iii)
     above.

          (e) Form S-4. The Form S-4 shall have become
     effective under the Securities Act and shall not be the
     subject of any stop order or proceedings seeking a stop
     order.

          (f) NYSE Listing. The shares of UC Common Stock
     issuable to DSI's stockholders pursuant to this


<PAGE>


     Agreement and under the DSI Stock Plans shall have been
     approved for listing on the NYSE, subject to official
     notice of issuance.

          (g) Pooling Letters. UC and DSI shall have
     received letters from each of Price Waterhouse LLP and
     Ernst & Young LLP, dated as of the Closing Date,
     addressed to UC and DSI, stating in substance that the
     Merger will qualify as a pooling of interests
     transaction under Opinion 16 of the Accounting
     Principles Board and applicable SEC rules and
     regulations.

          SECTION 6.02. Conditions to Obligations of UC. The
obligation of UC to effect the Merger is further subject to
satisfaction or waiver of the following conditions:

          (a) Representations and Warranties. The
     representations and warranties of DSI set forth in this
     Agreement that are qualified as to materiality shall be
     true and correct, and the representations and
     warranties of DSI set forth in this Agreement that are
     not so qualified shall be true and correct in all
     material respects, in each case as of the date of this
     Agreement and as of the Closing Date as though made on
     and as of the Closing Date, except to the extent such
     representations and warranties expressly relate to an
     earlier date (in which case as of such date), and UC
     shall have received a certificate signed on behalf of
     DSI by the chief executive officer and the chief
     financial officer of DSI to such effect.

          (b) Performance of Obligations of DSI. DSI shall
     have performed in all material respects all obligations
     required to be performed by it under this Agreement at
     or prior to the Closing Date, and UC shall have
     received a certificate signed on behalf of DSI by the
     chief executive officer and the chief financial officer
     of DSI to such effect.

          (c) Tax Opinions. UC shall have received from
     Cravath, Swaine & Moore, counsel to UC, on the date of
     the Joint Proxy Statement and on the Closing Date,
     opinions, in each case dated as of such respective
     dates and stating that the Merger will be treated for
     federal income tax purposes as a reorganization within
     the meaning of Section 368(a) of the Code and that UC
     and DSI will each be a party to that reorganization


<PAGE>


     within the meaning of Section 368(b) of the Code and
     that no gain or loss will be recognized by the
     shareholders of DSI upon their exchange of DSI stock
     for UC stock under Section 354 of the Code (except to
     the extent such a shareholder receives cash in lieu of
     fractional shares). In rendering such opinions, counsel
     for UC shall be entitled to rely upon representations
     of officers of UC, DSI and stockholders of DSI
     substantially in the form of Exhibits D, E and F
     hereto.

          (d) No Material Adverse Change. At any time after
     the date of this Agreement there shall not have
     occurred any material adverse change relating to DSI.

          SECTION 6.03. Conditions to Obligation of DSI. The
obligation of DSI to effect the Merger is further subject to
satisfaction or waiver of the following conditions:

          (a) Representations and Warranties. The
     representations and warranties of UC set forth in this
     Agreement that are qualified as to materiality shall be
     true and correct, and the representations and
     warranties of UC set forth in this Agreement that are
     not so qualified shall be true and correct in all
     material respects, in each case as of the date of this
     Agreement and as of the Closing Date as though made on
     and as of the Closing Date, except to the extent such
     representations expressly relate to an earlier date (in
     which case as of such date), and DSI shall have
     received a certificate signed on behalf of UC by the
     chief executive officer and the chief financial officer
     of UC to such effect.

          (b) Performance of Obligations of UC. UC shall
     have performed in all material respects all obligations
     required to be performed by it under this Agreement at
     or prior to the Closing Date, and DSI shall have
     received a certificate signed on behalf of UC by the
     chief executive officer and the chief financial officer
     of UC to such effect.

          (c) Tax Opinions. DSI shall have received from
     Jones, Day, Reavis & Pogue, counsel to DSI, on the date
     of the Joint Proxy Statement and on the Closing Date,
     opinions, in each case dated as of such respective
     dates and stating that the Merger will be treated for


<PAGE>


     federal income tax purposes as a reorganization within
     the meaning of Section 368(a) of the Code and that UC
     and DSI will each be a party to that reorganization
     within the meaning of Section 368(b) of the Code and
     that no gain or loss will be recognized by the
     shareholders of DSI upon their exchange of DSI stock
     for UC stock under Section 354 of the Code (except to
     the extent such a shareholder receives cash in lieu of
     fractional shares). In rendering such opinions, counsel
     for DSI shall be entitled to rely upon representations
     of officers of UC, DSI and stockholders of DSI
     substantially in the form of Exhibits D, E and F
     hereto.

          (d) No Material Adverse Change. At any time after
     the date of this Agreement there shall not have
     occurred any material adverse change relating to UC.

          SECTION 6.04. Frustration of Closing Conditions.
Neither UC nor DSI may rely on the failure of any condition
set forth in Section 6.01, 6.02 or 6.03, as the case may be,
to be satisfied if such failure was caused by such party's
failure to use reasonable efforts to consummate the Merger
and the other transactions contemplated by this Agreement
and the Option Agreements, as required by and subject to
Section 5.05.


                         ARTICLE VII

              Termination, Amendment and Waiver

          SECTION 7.01. Termination. This Agreement may be
terminated at any time prior to the Effective Time, whether
before or after the DSI Stockholder Approval or the UC
Stockholder Approval:

          (a) by mutual written consent of UC and DSI;

          (b) by either UC or DSI:

               (i) if the Merger shall not have been
          consummated by February 28, 1997; provided,
          however, that the right to terminate this
          Agreement pursuant to this Section 7.01(b)(i)
          shall not be available to any party whose failure
          to perform any of its obligations under this


<PAGE>


          Agreement results in the failure of the Merger to
          be consummated by such time;

               (ii) if the DSI Stockholder Approval shall
          not have been obtained at a DSI Stockholders
          Meeting duly convened therefor or at any
          adjournment or postponement thereof;

               (iii) if the UC Stockholder Approval shall
          not have been obtained at a UC Stockholders
          Meeting duly convened therefor or at any
          adjournment or postponement thereof; or

               (iv) if any Governmental Entity shall have
          issued a Restraint or taken any other action
          permanently enjoining, restraining or otherwise
          prohibiting the consummation of the Merger or any
          of the other transactions contemplated by this
          Agreement and the Option Agreements and such
          Restraint or other action shall have become final
          and nonappealable;

          (c) by UC, if DSI shall have breached or failed to
     perform in any material respect any of its
     representations, warranties, covenants or other
     agreements contained in this Agreement, which breach or
     failure to perform (A) would give rise to the failure
     of a condition set forth in Section 6.02(a) or (b), and
     (B) cannot be or has not been cured within 30 days
     after the giving of written notice to DSI of such
     breach (a "DSI Material Breach") (provided that UC is
     not then in UC Material Breach (as defined in Section
     7.01(g)) of any representation, warranty, covenant or
     other agreement contained in this Agreement);

          (d) by UC in accordance with Section 4.03(b);
     provided that it has complied with all provisions
     thereof, including the notice provisions therein, and
     that it complies with applicable requirements of
     Section 5.09;

          (e) by UC if (i) the Board of Directors of DSI or
     any committee thereof shall have withdrawn or modified
     in a manner adverse to UC its approval or
     recommendation of the Merger or this Agreement or
     failed to reconfirm its recommendation within 
     15 business days after a written request to do so, or


<PAGE>


     approved or recommended any DSI Takeover Proposal or (ii) the
     Board of Directors of DSI or any committee thereof shall have
     resolved to take any of the foregoing actions;

          (f) by UC, if DSI or any of its officers, directors,
     employees, representatives or agents shall take any of the
     actions that would be proscribed by Section 4.02 but for the
     exceptions therein allowing certain actions to be taken pursuant
     to the proviso in the first sentence of Section 4.02(a) or the
     second sentence of Section 4.02(b);

          (g) by DSI, if UC shall have breached or failed to perform
     in any material respect any of its representations, warranties,
     covenants or other agreements contained in this Agreement, which
     breach or failure to perform (A) would give rise to the failure
     of a condition set forth in Section 6.03(a) or (b), and (B)
     cannot be or has not been cured within 30 days after the giving
     of written notice to UC of such breach (a "UC Material Breach")
     (provided that DSI is not then in DSI Material Breach of any
     representation, warranty, covenant or other agreement contained
     in this Agreement);

          (h) by DSI in accordance with Section 4.02(b); provided that
     it has complied with all provisions thereof, including the notice
     provisions therein, and that it complies with applicable
     requirements of Section 5.09;

          (i) by DSI if (i) the Board of Directors of UC or any
     committee thereof shall have withdrawn or modified in a manner
     adverse to DSI its approval or recommendation of the Merger, this
     Agreement or the issuance of UC Common Stock in connection with
     the Merger, or failed to reconfirm its recommendation within 15
     business days after a written request to do so, or approved or
     recommended any UC Takeover Proposal or (ii) the Board of
     Directors of UC or any committee thereof shall have resolved to
     take any of the foregoing actions; or

          (j) by DSI, if UC or any of its officers, directors,
     employees, representatives or agents shall take any of the
     actions that would be proscribed by Section 4.03 but for the
     exceptions therein allowing 

<PAGE>

     certain actions to be taken pursuant to the proviso in the first
     sentence of Section 4.03(a) or the second sentence of Section
     4.03(b).

          SECTION 7.02. Effect of Termination. In the event of
termination of this Agreement by either DSI or UC as provided in
Section 7.01, this Agreement shall forthwith become void and have no
effect, without any liability or obligation on the part of UC or DSI,
other than the provisions of Section 3.01(p), Section 3.02(p), the
last sentence of Section 5.04, Section 5.09, this Section 7.02 and
Article VIII and except to the extent that such termination results
from the willful and material breach by a party of any of its
representations, warranties, covenants or agreements set forth in this
Agreement.

          SECTION 7.03. Amendment. This Agreement may be amended by
the parties at any time before or after the DSI Stockholder Approval
or the UC Stockholder Approval; provided, however, that after any such
approval, there shall not be made any amendment that by law requires
further approval by the stockholders of DSI or UC without the further
approval of such stockholders. This Agreement may not be amended
except by an instrument in writing signed on behalf of each of the
parties.

          SECTION 7.04. Extension; Waiver. At any time prior to the
Effective Time, a party may (a) extend the time for the performance of
any of the obligations or other acts of the other parties, (b) waive
any inaccuracies in the representations and warranties of the other
parties contained in this Agreement or in any document delivered
pursuant to this Agreement or (c) subject to the proviso of Section
7.03, waive compliance by the other party with any of the agreements
or conditions contained in this Agreement. Any agreement on the part
of a party to any such extension or waiver shall be valid only if set
forth in an instrument in writing signed on behalf of such party. The
failure of any party to this Agreement to assert any of its rights
under this Agreement or otherwise shall not constitute a waiver of
such rights.

          SECTION 7.05. Procedure for Termination, Amendment,
Extension or Waiver. A termination of this Agreement pursuant to
Section 7.01, an amendment of this Agreement pursuant to Section 7.03
or an extension or waiver pursuant to Section 7.04 shall, in order to
be effective, require, in the case of UC or DSI, action by its Board
of


<PAGE>


Directors or, with respect to any amendment to this
Agreement, the duly authorized committee of its Board of
Directors.


                        ARTICLE VIII

                     General Provisions

          SECTION 8.01. Nonsurvival of Representations and
Warranties. None of the representations and warranties in
this Agreement or in any instrument delivered pursuant to
this Agreement shall survive the Effective Time. This
Section 8.01 shall not limit any covenant or agreement of
the parties which by its terms contemplates performance
after the Effective Time.

          SECTION 8.02. Notices. All notices, requests,
claims, demands and other communications under this
Agreement shall be in writing and shall be deemed given if
delivered personally, telecopied (which is confirmed) or
sent by overnight courier (providing proof of delivery) to
the parties at the following addresses (or at such other
address for a party as shall be specified by like notice):

          (a) if to UC, to

              Ultramar Corporation
              Two Pickwick Plaza, Suite 300
              Greenwich, Connecticut 06830

              Telecopy No.:  (203) 622-7007

              Attention:  Patrick J. Guarino, Esq.

              with a copy to:

              Cravath, Swaine & Moore
              Worldwide Plaza
              825 Eighth Avenue
              New York, New York 10019

              Telecopy No.:  (212) 474-3700

              Attention: William P. Rogers, Jr.; and


<PAGE>


          (b) if to DSI, to

              Diamond Shamrock, Inc.
              9830 Colonnade Blvd.
              San Antonio, Texas 78230

              Telecopy No.:  (210) 641-8885

              Attention:  Timothy J. Fretthold, Esq.

              with a copy to:

              Jones, Day, Reavis & Pogue
              599 Lexington Avenue, 30th Floor
              New York, New York 10022

              Telecopy No.: (212) 755-7306

              Attention:  Robert A. Profusek, Esq.

          SECTION 8.03. Definitions. For purposes of this
Agreement:

          (a) an "affiliate" of any person means another
     person that directly or indirectly, through one or more
     intermediaries, controls, is controlled by, or is under
     common control with, such first person;

          (b) "material adverse change" or "material adverse
     effect" means, when used in connection with DSI or UC,
     any change, effect, event or occurrence that is
     materially adverse to the business, financial condition
     or results of operations of such party and its
     subsidiaries taken as a whole other than any change,
     effect, event or occurrence relating to the United
     States economy in general or to the petroleum refining
     and marketing industry in general, and not specifically
     relating to DSI or UC or their respective subsidiaries,
     and the terms "material" and "materially" have
     correlative meanings;

          (c) "person" means an individual, corporation,
     partnership, limited liability company, joint venture,
     association, trust, unincorporated organization or
     other entity;

          (d) a "subsidiary" of any person means another
     person, an amount of the voting securities, other


<PAGE>


     voting ownership or voting partnership interests of
     which is sufficient to elect at least a majority of its
     Board of Directors or other governing body (or, if
     there are no such voting interests, 50% or more of the
     equity interests of which) is owned directly or
     indirectly by such first person; and

          (e) "knowledge" of any person which is not an
     individual means the knowledge of such person's
     executive officers after reasonable inquiry.

          SECTION 8.04. Interpretation. When a reference is
made in this Agreement to an Article, Section or Exhibit,
such reference shall be to an Article or Section of, or an
Exhibit to, this Agreement unless otherwise indicated. The
table of contents and headings contained in this Agreement
are for reference purposes only and shall not affect in any
way the meaning or interpretation of this Agreement.
Whenever the words "include", "includes" or "including" are
used in this Agreement, they shall be deemed to be followed
by the words "without limitation". The words "hereof",
"herein" and "hereunder" and words of similar import when
used in this Agreement shall refer to this Agreement as a
whole and not to any particular provision of this Agreement.
All terms defined in this Agreement shall have the defined
meanings when used in any certificate or other document made
or delivered pursuant hereto unless otherwise defined
therein. The definitions contained in this Agreement are
applicable to the singular as well as the plural forms of
such terms and to the masculine as well as to the feminine
and neuter genders of such term. Any agreement, instrument
or statute defined or referred to herein or in any agreement
or instrument that is referred to herein means such
agreement, instrument or statute as from time to time
amended, modified or supplemented, including (in the case of
agreements or instruments) by waiver or consent and (in the
case of statutes) by succession of comparable successor
statutes and references to all attachments thereto and
instruments incorporated therein. References to a person are
also to its permitted successors and assigns.

          SECTION 8.05. Counterparts. This Agreement may be
executed in one or more counterparts, all of which shall be
considered one and the same agreement and shall become
effective when one or more counterparts have been signed by
each of the parties and delivered to the other parties.


<PAGE>


          SECTION 8.06. Entire Agreement; No Third-Party
Beneficiaries. This Agreement (including the documents and
instruments referred to herein), the Option Agreements and
the Confidentiality Agreement (a) constitute the entire
agreement, and supersede all prior agreements and
understandings, both written and oral, among the parties
with respect to the subject matter of this Agreement and (b)
except for the provisions of Article II, Section 5.06 and
Section 5.08, are not intended to confer upon any person
other than the parties any rights or remedies.

          SECTION 8.07. Governing Law. This Agreement shall
be governed by, and construed in accordance with, the laws
of the State of Delaware, regardless of the laws that might
otherwise govern under applicable principles of conflict of
laws thereof.

          SECTION 8.08. Assignment. Neither this Agreement
nor any of the rights, interests or obligations under this
Agreement shall be assigned, in whole or in part, by
operation of law or otherwise by either of the parties
hereto without the prior written consent of the other party.
Any assignment in violation of the preceding sentence shall
be void. Subject to the preceding sentence, this Agreement
will be binding upon, inure to the benefit of, and be
enforceable by, the parties and their respective successors
and assigns.

          SECTION 8.09. Enforcement. The parties agree that
irreparable damage would occur and that the parties would
not have any adequate remedy at law in the event that any of
the provisions of this Agreement were not performed in
accordance with their specific terms or were otherwise
breached. It is accordingly agreed that the parties shall be
entitled to an injunction or injunctions to prevent breaches
of this Agreement and to enforce specifically the terms and
provisions of this Agreement in any federal court located in
the State of Delaware or in Delaware state court, this being
in addition to any other remedy to which they are entitled
at law or in equity. In addition, each of the parties hereto
(a) consents to submit itself to the personal jurisdiction
of any federal court located in the State of

<PAGE>


Delaware or any Delaware state court in the event any
dispute arises out of this Agreement or any of the
transactions contemplated by this Agreement, (b) agrees
that it will not attempt to deny or defeat such personal
jurisdiction by motion or other request for leave from any
such court, and (c) agrees that it will not bring any
action relating to this Agreement or any of the transactions
contemplated by this Agreement in any court other than a
federal court sitting in the State of Delaware or a
Delaware state court.


          IN WITNESS WHEREOF, UC and DSI have caused this
Agreement to be signed by their respective officers
thereunto duly authorized, all as of the date first written
above.


                              ULTRAMAR CORPORATION,

                                by
                                   /s/ Jean Gaulin
                                  ---------------------------
                                  Name:   Jean Gaulin
                                  Title:  Chairman of the
                                          Board and Chief
                                          Executive Officer


                              DIAMOND SHAMROCK, INC.,

                                 by
                                    /s/ Roger R. Hemminghaus
                                   ---------------------------
                                   Name:  Roger R. Hemminghaus
                                   Title: Chairman of the
                                          Board, Chief
                                          Executive Officer
                                          and President


<PAGE>


                                                   EXHIBIT A
                                     TO THE MERGER AGREEMENT


                Amendments to UC Certificate
                of Incorporation and By-laws

          The certificate of incorporation of UC shall be
amended as of the Effective Time so that (i) it reads in its
entirety as it exists on the date of the Agreement and as
otherwise set forth herein, (ii) Article FIRST of such
certificate of incorporation reads in its entirety as
follows: "The name of the Corporation is Ultramar Diamond
Shamrock Corp. (hereinafter the "Corporation").", (iii)
Section 1 of Article FOURTH of such certificate of
incorporation reads in its entirety as follows: "The total
number of shares which the Corporation shall have authority
to issue is 275,000,000 shares, consisting of (a)
250,000,000 shares of common stock, par value $.01 per share
(the "Common Stock"), and (ii) 25,000,000 shares of
preferred stock, par value $.01 per share (the "Preferred
Stock").", and (iv) there shall be added an Article Eleventh
which reads in its entirety as follows: "ELEVENTH: With
respect to any action required or permitted to be taken by
the stockholders of the Corporation at any annual or special
meeting, unless required by law or determined by the
chairman of the meeting to be advisable, the vote on any
matter, including the election of directors, need not be by
written ballot."

          The by-laws of UC shall be amended as of the
Effective Time so that they read in their entirety as they
exist on the date of the Agreement except that:

          (i) Section 1 of Article IV of such by-laws reads
in its entirety as follows:

          "SECTION 1. General. The officers of the
     Corporation shall be chosen by the Board of Directors
     and shall be a Chairman of the Board of Directors (who
     must be a director), a Vice Chairman of the Board of
     Directors (who also must be a director), a Chief
     Executive Officer, a President and Chief Operating
     Officer, a Secretary and a Treasurer. The Board of
     Directors, in its discretion, may also choose one or
     more Vice Presidents (including, without limitation,
     Assistant, Executive, Senior and Group), Assistant
     Secretaries, Assistant Treasurers and other officers.
     Any number of offices may be held by the same person,
     unless otherwise prohibited by law, the Certificate of
     Incorporation or these By-laws. The officers of the
     Corporation need not be stockholders of the Corporation


<PAGE>

     nor, except in the case of the Chairman of the Board of
     Directors and the Vice Chairman of the Board of
     Directors, need such officers be directors of the
     Corporation.";

          (ii) Sections 4, 5 and 6 of Article IV of such
by-laws read in their entirety as follows:

          "SECTION 4. Chairman and Vice Chairman of the
     Board of Directors. The Chairman of the Board of
     Directors shall preside at all meetings of the
     stockholders and of the Board of Directors. Except
     where by law the signature of the Chief Executive
     Officer or the President and Chief Operating Officer is
     required, the Chairman of the Board of Directors shall
     possess the same power as the Chief Executive Officer
     or the President and Chief Operating Officer to sign
     all contracts, certificates and other instruments of
     the Corporation which may be authorized by the Board of
     Directors. During the absence or disability of the
     Chief Executive Officer or President and Chief
     Operating Officer, the Chairman of the Board of
     Directors shall exercise all the powers and discharge
     all the duties of the Chief Executive Officer or
     President and Chief Operating Officer, as applicable.
     The Chairman of the Board of Directors shall also
     perform such other duties and may exercise such other
     powers as from time to time may be assigned to him by
     these By-laws or by the Board of Directors. The Vice
     Chairman of the Board of Directors shall, during the
     absence or disability of the Chairman of the Board of
     Directors, have the powers and perform the duties of
     the Chairman of the Board of Directors and shall also
     perform such other duties and may exercise such other
     powers as from time to time may be assigned to him by
     the Board of Directors. Notwithstanding anything in
     these By-laws to the contrary, the Chairman of the
     Board of Directors and the Vice Chairman of the Board
     of Directors may only be removed from such offices (but
     not as directors) by an affirmative vote of the
     majority of the entire Board of Directors.

          "SECTION 5. Chief Executive Officer and President
     and Chief Operating Officer. The Chief Executive
     Officer shall, subject to the control of the Board of
     Directors and the Chairman of the Board of Directors
     (or during his absence or disability, the Vice Chairman
     of the Board of Directors), have general supervision of


<PAGE>


     the business and affairs of the Corporation and shall
     see that all orders and resolutions of the Board of
     Directors are carried into effect. He shall possess the
     power to execute all bonds, mortgages, contracts and
     other instruments of the Corporation requiring a seal,
     under the seal of the Corporation, except where
     required or permitted by law to be otherwise signed and
     executed and except that the other officers of the
     Corporation may sign and execute documents when so
     authorized by these By-laws, the Board of Directors or
     the Chief Executive Officer. In the absence or
     disability of both the Chairman of the Board of
     Directors and the Vice Chairman of the Board of
     Directors, the Chief Executive Officer shall preside at
     all meetings of the stockholders and the Board of
     Directors. The Chief Executive Officer shall also
     perform such other duties and may exercise such other
     powers as from time to time may be assigned to him by
     these By-laws or by the Board of Directors. The
     President and Chief Operating Officer (hereinafter
     sometimes referred to only as the "President") shall,
     subject to the direction and control of the Board of
     Directors, and the supervision of the Chairman of the
     Board of Directors (or during his absence or
     disability, the Vice Chairman of the Board of
     Directors) and the Chief Executive Officer, have
     general supervision of the business operations of the
     Corporation. The President and Chief Operating Officer
     shall, during the absence or disability of the Chief
     Executive Officer, have the powers and perform the
     duties of the Chief Executive Officer and shall also
     perform such other duties and may exercise such other
     powers as from time to time may be assigned to him by
     these By-laws or the Board of Directors.
     Notwithstanding anything in these By-laws to the
     contrary, the Chief Executive Officer and the President
     and Chief Operating Officer may only be removed from
     such offices by an affirmative vote of the majority of
     the entire Board of Directors.

          "SECTION 6. Vice Presidents. At the request of the
     Chief Executive Officer or in his absence or in the
     event of his inability or refusal to act (and if there
     be no Chairman of the Board of Directors, Vice Chairman
     of the Board of Directors or President and Chief
     Operating Officer), the Vice President or the Vice
     Presidents if there is more than one (in the order
     designated by the Board of Directors) shall perform the


<PAGE>


     duties of the Chief Executive Officer, and when so
     acting, shall have all the powers of and be subject to
     all the restrictions upon the Chief Executive Officer.
     Each Vice President shall perform such other duties and
     have such other powers as the Board of Directors from
     time to time may prescribe. If there be no Chairman of
     the Board of Directors, no Vice Chairman of the Board
     of Directors, no President and Chief Operating Officer
     and no Vice President, the Board of Directors shall
     designate the officer of the Corporation who, in the
     absence of the Chief Executive Officer or in the event
     of the inability or refusal of the Chief Executive
     Officer to act, shall perform the duties of the Chief
     Executive Officer, and when so acting, shall have all
     the powers of and be subject to all the restrictions
     upon the Chief Executive Officer."; and

          (iii) Article VIII of such by-laws reads in its
entirety as follows:

                        "ARTICLE VIII

                      "Indemnification


          "SECTION 1. Right to Indemnification. Each 
person who was or is made a party or is threatened to be
made a party to or is otherwise involved in any action, suit
or proceeding, whether civil, criminal, administrative or
investigative (hereinafter a "proceeding"), by reason of the
fact that he or she is or was a director or an officer of
the Corporation or is or was serving at the request of the
Corporation as a director, officer, employee or agent of
another corporation or of a partnership, joint venture,
trust or other enterprise, including service with respect to
an employee benefit plan (hereinafter an "indemnitee"),
whether the basis of such proceeding is alleged action in an
official capacity as a director, officer, employee or agent
or in any other capacity while serving as a director,
officer, employee or agent, shall be indemnified and held
harmless by the Corporation to the fullest extent permitted
or required by the Delaware General Corporation Law, as the
same exists or may hereafter be amended (but, in the case of
any such amendment, only to the extent that such amendment
permits the Corporation to provide broader indemnification
rights than such law permitted the Corporation to provide
prior to such amendment), against all expense, liability and
loss (including attorneys' fees, judgments, fines, ERISA


<PAGE>


excise taxes or penalties and amounts paid in settlement)
reasonably incurred or suffered by such indemnitee in
connection therewith; provided, however, that, except as
provided in Section 3 of this Article VIII with respect to
proceedings to enforce rights to indemnification, the
Corporation shall indemnify any such indemnitee in connec-
tion with a proceeding (or part thereof) initiated by such
indemnitee only if such proceeding (or part thereof) was
authorized by the Board of Directors of the Corporation.

          "SECTION 2. Right to Advancement of Expenses. The
right to indemnification conferred in Section 1 of this
Article VIII shall include the right to be paid by the
Corporation the expenses (including, without limitation,
attorneys' fees and expenses) incurred in defending any such
proceeding in advance of its final disposition (hereinafter
an "advancement of expenses"); provided, however, that, if
the Delaware General Corporation Law so requires, an
advancement of expenses incurred by an indemnitee in his or
her capacity as a director or officer (and not in any other
capacity in which service was or is rendered by such
indemnitee, including, without limitation, service to an
employee benefit plan) shall be made only upon delivery to
the Corporation of an undertaking (hereinafter an
"undertaking"), by or on behalf of such indemnitee, to repay
all amounts so advanced if it shall ultimately be determined
by final judicial decision from which there is no further
right to appeal (hereinafter a "final adjudication") that
such indemnitee is not entitled to be indemnified for such
expenses under this Section 2 or otherwise. The rights to
indemnification and to the advancement of expenses conferred
in Sections 1 and 2 of this Article VIII shall be contract
rights and such rights shall continue as to an indemnitee who
has ceased to be a director, officer, employee or agent and
shall inure to the benefit of the indemnitee's heirs,
executors and administrators.

          "SECTION 3. Right of Indemnitee to Bring Suit. 
If a claim under Section 1 or 2 of this Article VIII is not
paid in full by the Corporation within 60 calendar days 
after a written claim has been received by the Corporation,
except in the case of a claim for an advancement of
expenses, in which case the applicable period shall be 
20 calendar days, the indemnitee may at any time thereafter
bring suit against the Corporation to recover the unpaid
amount of the claim. If successful in whole or in part in
any such suit, or in a suit brought by the Corporation to
recover an advancement of expenses pursuant to the terms of


<PAGE>


an undertaking, the indemnitee shall be entitled to be paid
also the expense of prosecuting or defending such suit. In
(i) any suit brought by the indemnitee to enforce a right to
indemnification hereunder (but not in a suit brought by the
indemnitee to enforce a right to an advancement of expenses)
it shall be a defense that, and (ii) any suit brought by the
Corporation to recover an advancement of expenses pursuant
to the terms of an undertaking, the Corporation shall be
entitled to recover such expenses upon a final adjudication
that, the indemnitee has not met any applicable standard for
indemnification set forth in the Delaware General Corpora-
tion Law. Neither the failure of the Corporation (including
its Board of Directors, independent legal counsel or stock-
holders) to have made a determination prior to the com-
mencement of such suit that indemnification of the indemni-
tee is proper in the circumstances because the indemnitee
has met the applicable standard of conduct set forth in the
Delaware General Corporation Law, nor an actual
determination by the Corporation (including its Board of
Directors, independent legal counsel or stockholders) that
the indemnitee has not met such applicable standard of
conduct, shall create a presumption that the indemnitee has
not met the applicable standard of conduct or, in the case
of such a suit brought by the indemnitee, be a defense to
such suit. In any suit brought by the indemnitee to enforce
a right to indemnification or to an advancement of expenses
hereunder, or brought by the Corporation to recover an
advancement of expenses pursuant to the terms of an under-
taking, the burden of proving that the indemnitee is not
entitled to be indemnified, or to such advancement of
expenses, under this Article VIII or otherwise shall be on
the Corporation.

          "SECTION 4. Non-Exclusivity of Rights. The rights
to indemnification and to the advancement of expenses
conferred in this Article VIII shall not be exclusive of any
other right which any person may have or hereafter acquire
under any statute, the Corporation's Certificate of
Incorporation, By-laws, agreement, vote of stockholders or
disinterested directors or otherwise.

          "SECTION 5. Insurance. The Corporation may
maintain insurance, at its expense, to protect itself and
any director, officer, employee or agent of the Corporation
or another corporation, partnership, joint venture, trust or
other enterprise against any expense, liability or loss,
whether or not the Corporation would have the power to


<PAGE>


indemnify such person against such expense, liability or
loss under the Delaware General Corporation Law.

          "SECTION 6. Indemnification of Employees and
Agents of the Corporation. The Corporation may, to the
extent authorized from time to time by the Board of
Directors, grant rights to indemnification and to the
advancement of expenses to any employee or agent of the
Corporation to the fullest extent of the provisions of this
Article with respect to the indemnification and advancement
of expenses of directors and officers of the Corporation."


<PAGE>



                                                   EXHIBIT B
                                     TO THE MERGER AGREEMENT



Board of Directors

          The Board of Directors of the Surviving
Corporation will consist of Roger R. Hemminghaus, Jean
Gaulin and ten other members, five of whom shall be
designated by each of UC and DSI. Roger R. Hemminghaus will
serve as Chairman of the Board of Directors and Jean Gaulin
will serve as Vice Chairman of the Board of Directors, and
in such capacities each shall be considered officers of the
Surving Corporation for the purposes of this Agreement,
including this Exhibit B and Section 1.06. Each class of the
Board of Directors will be comprised of four directors, of
which two shall be designated by each of UC and DSI. For the
purposes of this Exhibit B and Section 1.06, Jean Gaulin
shall be deemed designated by UC and Roger R. Hemminghaus
shall be deemed designated by DSI.


Committees of the Board of Directors and Chairmen of
Committees

          The Board of Directors shall initially have four
committees, the finance and planning committee, the
compensation committee, the audit review committee and the
public responsibility committee . Each committee will be
comprised of four directors, of which two shall be
designated by each of UC and DSI. UC will designate the
chairman of the finance and planning committee and the
compensation committee and DSI will designate the chairman
of the audit review committee and the public responsibility
committee.


Officers

Roger R. Hemminghaus          Chairman of the Board of
                              Directors and Chief Executive
                              Officer

Jean Gaulin                   Vice Chairman of the Board of
                              Directors, President and Chief
                              Operating Officer

T. J. Fretthold               Executive Vice President and
                              Chief Administrative Officer

Patrick J. Guarino            Executive Vice President,
                              General Counsel and Secretary



<PAGE>


W. R. Klesse                  Executive Vice President
                              Logistics and Supply

J. Robert Mehall              Executive Vice President
                              Corporate Development

H. Pete Smith                 Executive Vice President and
                              Chief Financial Officer

Joel Mascitelli               Senior Vice President Refining
                              West Coast

Paul Eisman                   Senior Vice President Refining
                              Southwest

Alain Ferland                 President Ultramar Limited

Christopher Havens            President Ultramar Energy

A. W. O'Donnell               President Marketing Southwest
                              and West Coast


<PAGE>


                                                   EXHIBIT C
                                     TO THE MERGER AGREEMENT


                  Form of Affiliate Letter

Dear Sirs:

          The undersigned, a holder of shares of common
stock, par value $.01 per share ("DSI Common Stock"), of
Diamond Shamrock, Inc., a Delaware corporation ("DSI"), or
of shares of 5% Cumulative Convertible Preferred Stock, par
value $.01 per share ("DSI Convertible Preferred Stock"), of
DSI, is entitled to receive in connection with the merger
(the "Merger") of DSI with and into Ultramar Corporation, a
Delaware corporation ("UC"), securities (the "UC
Securities") of UC. The undersigned acknowledges that the
undersigned may be deemed an "affiliate" of DSI within the
meaning of Rule 145 ("Rule 145") promulgated under the
Securities Act of 1933, as amended (the "Securities Act"),
by the Securities and Exchange Commission (the "SEC") and
may be deemed an "affiliate" of DSI for purposes of
qualifying the Merger for pooling of interests accounting
treatment under Opinion 16 of the Accounting Principles
Board and applicable SEC rules and regulations, although
nothing contained herein should be construed as an admission
of either such fact.

          If in fact the undersigned were an affiliate under
the Securities Act, the undersigned's ability to sell,
assign or transfer the UC Securities received by the
undersigned in exchange for any shares of DSI Common Stock
or DSI Convertible Preferred Stock in connection with the
Merger may be restricted unless such transaction is
registered under the Securities Act or an exemption from
such registration is available. The undersigned understands
that such exemptions are limited and the undersigned has
obtained or will obtain advice of counsel as to the nature
and conditions of such exemptions, including information
with respect to the applicability to the sale of such
securities of Rules 144 and 145(d) promulgated under the
Securities Act. The undersigned understands that UC will not
be required to maintain the effectiveness of any
registration statement under the Securities Act for the
purposes of resale of UC Securities by the undersigned.

          The undersigned hereby represents to and covenants
with UC that the undersigned will not sell, assign or
transfer any of the UC Securities received by the
undersigned in exchange for shares of DSI Common Stock or
DSI Convertible Preferred Stock in connection with the
Merger except (i) pursuant to an effective registration


<PAGE>


statement under the Securities Act, (ii) in conformity with
the volume and other limitations of Rule 145 or (iii) in a
transaction which, in the opinion of the general counsel of
UC or other counsel reasonably satisfactory to UC or as
described in a "no-action" or interpretive letter from the
Staff of the SEC specifically issued with respect to a
transaction to be engaged in by the undersigned, is not
required to be registered under the Securities Act;
provided, however, that in any such case, such sale,
assignment or transfer shall only be permitted if, in the
opinion of counsel of UC, such transaction would not have,
directly or indirectly, any adverse consequences for UC with
respect to the treatment of the Merger for tax purposes.

          The undersigned hereby further represents to and
covenants with UC that the undersigned has not, within the
preceding 30 days, sold, transferred or otherwise disposed
of any shares of DSI Common Stock or DSI Convertible
Preferred Stock held by the undersigned and that the
undersigned will not sell, transfer or otherwise dispose of
any UC Securities received by the undersigned in connection
with the Merger until after such time as results covering at
least 30 days of combined operations of DSI and UC have been
published by UC, in the form of a quarterly earnings report,
an effective registration statement filed with the SEC, a
report to the SEC on Form 10-K, 10-Q or 8-K, or any other
public filing or announcement which includes such combined
results of operations.

          In the event of a sale or other disposition by the
undersigned of UC Securities pursuant to Rule 145, the
undersigned will supply UC with evidence of compliance with
such Rule, in the form of a letter in the form of Annex I
hereto and the opinion of counsel or no-action letter
referred to above. The undersigned understands that UC may
instruct its transfer agent to withhold the transfer of any
UC Securities disposed of by the undersigned, but that
(provided such transfer is not prohibited by any other
provision of this letter agreement) upon receipt of such
evidence of compliance, UC shall cause the transfer agent to
effectuate the transfer of the UC Securities sold as
indicated in such letter.

               UC covenants that it will take all such actions
as may be reasonably available to it to permit the sale or
other disposition of UC Securities by the undersigned under
Rule 145 in accordance with the terms thereof.


<PAGE>


          The undersigned acknowledges and agrees that the
legends set forth below will be placed on certificates
representing UC Securities received by the undersigned in
connection with the Merger or held by a transferee thereof,
which legends will be removed by delivery of substitute
certificates upon receipt of an opinion in form and
substance reasonably satisfactory to UC from independent
counsel reasonably satisfactory to UC to the effect that
such legends are no longer required for purposes of the
Securities Act.

          There will be placed on the certificates for UC
Securities issued to the undersigned, or any substitutions
therefor, a legend stating in substance:

          "The shares represented by this certificate were
     issued pursuant to a business combination which is
     being accounted for as a pooling of interests, in a
     transaction to which Rule 145 promulgated under the
     Securities Act of 1933 applies. The shares have not
     been acquired by the holder with a view to, or for
     resale in connection with, any distribution thereof
     within the meaning of the Securities Act of 1933. The
     shares may not be sold, pledged or otherwise
     transferred (i) until such time as Ultramar Diamond
     Shamrock Corp. shall have published financial results
     covering at least 30 days of combined operations after
     the Effective Time and (ii) except in accordance with
     an exemption from the registration requirements of the
     Securities Act of 1933."

          The undersigned acknowledges that (i) the
undersigned has carefully read this letter and understands
the requirements hereof and the limitations imposed upon the
distribution, sale, transfer or other disposition of UC
Securities and (ii) the receipt by UC of this letter is an
inducement to UC's obligations to consummate the Merger.


                              Very truly yours,



Dated:


<PAGE>


                                                     ANNEX I
                                                TO EXHIBIT C



[Name]                                                [Date]


          On                    , the undersigned sold the
securities of Ultramar Diamond Shamrock Corp., formerly
named Ultramar Corporation ("UC"), described below in the
space provided for that purpose (the "Securities"). The
Securities were received by the undersigned in connection
with the merger of Diamond Shamrock, Inc., a Delaware
corporation, with and into UC.

          Based upon the most recent report or statement
filed by UC with the Securities and Exchange Commission, the
Securities sold by the undersigned were within the
prescribed limitations set forth in paragraph (e) of Rule
144 promulgated under the Securities Act of 1933, as amended
(the "Securities Act").

          The undersigned hereby represents that the
Securities were sold in "brokers' transactions" within the
meaning of Section 4(4) of the Securities Act or in
transactions directly with a "market maker" as that term is
defined in Section 3(a)(38) of the Securities Exchange Act
of 1934, as amended. The undersigned further represents that
the undersigned has not solicited or arranged for the
solicitation of orders to buy the Securities, and that the
undersigned has not made any payment in connection with the
offer or sale of the Securities to any person other than to
the broker who executed the order in respect of such sale.


                              Very truly yours,





  [Space to be provided for description of the Securities.]


<PAGE>


                                                   EXHIBIT D
                                     TO THE MERGER AGREEMENT



                       [Letterhead of]

                   [Ultramar Corporation]






                                                   ___, 1996


Jones, Day, Reavis & Pogue
Metropolitan Square
1450 G Street, N.W.
Washington, D.C. 20005

Cravath, Swaine & Moore
Worldwide Plaza
825 Eighth Avenue
New York, New York 10019


Dear Sirs:

          In connection with the opinion to be delivered by
you pursuant to the Agreement and Plan of Merger (the
"Merger Agreement"), dated as of September 22, 1996, between
Ultramar Corporation, a Delaware corporation ("UC"), and
Diamond Shamrock, Inc., a Delaware corporation ("DSI"), I
certify, as of the date hereof, to my knowledge and belief,
after due inquiry, as follows:

          1. The facts relating to the contemplated merger
(the "Merger") of DSI with and into UC pursuant to the
Merger Agreement, as described in the Merger Agreement, the
documents described in Section 8.06 of the Merger Agreement
and the joint proxy statement/prospectus prepared by UC and
DSI, are, insofar as such facts pertain to UC, true, correct
and complete in all material respects.

          2. Except in the Merger, neither UC nor any
subsidiary of UC has acquired or will acquire, or has owned
in the past five years, any shares of common stock, par
value $0.01, per share, of DSI ("DSI Common Stock"), 5%
Cumulative Convertible Preferred Stock of DSI, par value
$.01 per share, or $2.00 Convertible Exchangeable Preferred
Stock of DSI, par value $.01 per share .


<PAGE>


          3. Cash payments to be made to stockholders of DSI
in lieu of fractional shares of Common Stock, par value
$0.01 per share, of UC ("UC Common Stock") that would
otherwise be issued to such stockholders in the Merger will
be made for the purpose of saving UC the expense and
inconvenience of issuing and transferring fractional shares
of UC Common Stock, and do not represent separately
bargained for consideration.

          4. UC has no plan or intention, following the
Merger, to reacquire any of the UC Common Stock issued in
the Merger.

          5. UC has no plan or intention, following the
Merger, to sell or otherwise dispose of any of the assets
held by DSI at the time of the Merger, except for
dispositions of such assets in the ordinary course of
business; provided, however, that UC may transfer assets of
DSI in a manner that is consistent with Section 368(a)(2)(C)
of the Internal Revenue Code of 1986, as amended (the
"Code").

          6. UC, DSI and the stockholders of DSI will each
pay their respective expenses, if any, incurred in
connection with the Merger.

          7. Following the Merger, UC will continue the
historic business of DSI or use a significant portion of
DSI's historic business assets in a business.

          8. UC is not an investment company as defined in
Section 368(a)(2)(F)(iii) and (iv) of the Code.

          9. UC will not take any position on any federal,
state or local income or franchise tax return, or take any
other action or reporting position, that is inconsistent
with the treatment of the Merger as a reorganization within
the meaning of Section 368(a)(1)(A) of the Code or with the
representations made in this letter, unless otherwise
required by a "determination" (as defined in Section
1313(a)(1) of the Code).

          10. None of the compensation received by any
stockholder-employee of DSI represents separate
consideration for, or is allocable to, any of their DSI
Common Stock. None of the UC Common Stock that will be
received by DSI stockholder-employees in the Merger
represents separately bargained for consideration which is


<PAGE>


allocable to any employment agreement or arrangement. The
compensation paid to any shareholder-employees will be for
services actually rendered and will be determined by
bargaining at arm's-length.

          11. There is no intercorporate indebtedness
existing between UC and DSI that was issued or acquired, or
will be settled, at a discount.

          12. The Merger Agreement and the documents
described in Section 8.06 of the Merger Agreement represent
the entire understanding of DSI and UC with respect to the
Merger.

          13. References in this letter to DSI, UC or any
subsidiary thereof shall not be considered to refer to any
DSI Benefit Plan or UC Benefit Plan (each as defined in the
Merger Agreement).



                              Ultramar Corporation,


                                By:
                                   --------------------------


<PAGE>


                                                   EXHIBIT E
                                     TO THE MERGER AGREEMENT



                       [Letterhead of]

                  [Diamond Shamrock, Inc.]



                                                   ___, 1996



Jones, Day, Reavis & Pogue
Metropolitan Square
1450 G Street, N.W.
Washington, D.C. 20005

Cravath, Swaine & Moore
Worldwide Plaza
825 Eighth Avenue
New York, New York 10019

Dear Sirs:

          In connection with the opinion to be delivered by
you pursuant to the Agreement and Plan of Merger (the
"Merger Agreement"), dated as of September 22, 1996, between
Ultramar Corporation, a Delaware corporation ("UC"), and
Diamond Shamrock, Inc., a Delaware corporation ("DSI"), I
certify, as of the date hereof, to my knowledge and belief,
after due inquiry, as follows:

          1. The facts relating to the contemplated merger
(the "Merger") of DSI with and into UC pursuant to the
Merger Agreement, as described in the Merger Agreement, the
documents described in Section 8.06 of the Merger Agreement
and the joint proxy statement/prospectus prepared by UC and
DSI, are, insofar as such facts pertain to DSI, true,
correct and complete in all material respects.

          2. Neither DSI nor any of its subsidiaries has
issued or acquired any shares of Common Stock, par value
$.01 of DSI ("DSI Common Stock"), 5% Cumulative Convertible
Preferred Stock of DSI, par value $.01 per share ("DSI
Convertible Preferred Stock") or $2.00 Convertible
Exchangeable Preferred Stock of DSI, par value $.01 per


<PAGE>


share, in contemplation of the Merger, or otherwise as part
of a plan of which the Merger is a part.

          3. There is no present plan or intention on the
part of the stockholders of DSI that own 5% or more of the
DSI Common Stock (or holders of DSI Convertible Preferred
Stock that would, upon conversion, own 5% or more of the DSI
Common Stock) ("DSI 5% Stockholders"), and DSI knows of no
present plan or intention on the part of the remaining
holders of DSI Common Stock or DSI Convertible Preferred
Stock, to sell, exchange or otherwise dispose of, reduce the
risk of loss (by short sale or otherwise) of the holding of,
enter into any contract or other arrangement with respect
to, or consent to the sale, exchange or other disposition of
(each of the foregoing, a "disposition"), any interest in
the shares of stock of UC ("UC Stock") received in the
Merger in exchange for such DSI Common Stock (other than by
the conversion of 5% Cumulative Convertible Preferred Stock
of UC, par value $.01 per share, into shares of common stock
of UC, par value $.01 per share ("UC Common Stock")) that
would reduce the ownership of UC Stock by former holders of
DSI Common Stock and DSI Preferred Stock to a number of
shares having a value, as of immediately prior to the
Merger, of less than 50% of the value of all of the
outstanding shares of DSI Stock as of such date. For
purposes of this representation, any "disposition" (as
defined above) of UC Stock will be treated as a reduction in
ownership thereof. In addition, for purposes of this
representation, shares of DSI Stock exchanged by holders of
DSI Stock for cash in lieu of fractional shares of UC Stock
will be treated as outstanding DSI Stock immediately prior
to the Merger. Moreover, for purposes of this
representation, shares of DSI Stock and shares of UC Stock
received in the Merger and sold, redeemed or disposed of
prior to or subsequent to the Merger, in contemplation
thereof or as part of a plan therewith, will be considered
in making this representation. For purposes of this
representation we have assumed that each DSI 5% Stockholder
has a plan or intention to sell for cash all the UC Stock
that it will receive in the Merger unless we have received
from such DSI 5% Stockholder a letter substantially in the
form of Exhibit F to the Merger Agreement with respect to
such UC Stock. The aggregate amount of DSI Common Stock
owned by DSI 5% Stockholders (or that would be so owned if
each such DSI 5% Stockholder were to convert all the shares
of DSI Convertible Preferred Stock owned by it) does not
exceed 40% of the amount of DSI Common Stock actually
outstanding on the date hereof (or that would be so


<PAGE>


outstanding if any such DSI 5% Stockholder were to convert
all the shares of DSI Convertible Preferred Stock owned by
it).

          4. DSI has no plan or intention to issue
additional shares of DSI Stock, except pursuant to the
exercise of employee stock options described in Section
3.01(c) of the Merger Agreement ("Employee Stock Options")
or the conversion of shares of the DSI Convertible Preferred
Stock.

          5. DSI, UC and the stockholders of DSI and UC will
each pay their respective expenses, if any, incurred in
connection with the Merger.

          6. Immediately prior to the Merger, DSI will not
have outstanding any warrants, options, convertible
securities or any other type of right pursuant to which any
person could acquire stock of DSI, other than the Employee
Stock Options and the DSI Convertible Preferred Stock.

          7. DSI is not an investment company as defined in
Section 368(a)(2)(F)(iii) and (iv) of the Internal Revenue
Code of 1986, as amended (the "Code").

          8. DSI will not take, and DSI is not aware of any
plan or intention of DSI stockholders to take, any position
on any Federal, state or local income or franchise tax
return, or take any other action or reporting position, that
is inconsistent with the treatment of the Merger as a
reorganization within the meaning of Section 368(a)(1)(A) of
the Code or with the representations made in this letter,
unless otherwise required pursuant to a "determination" (as
defined in Section 1313(a)(1) of the Code).

          9. None of the compensation received by any
stockholder-employee of DSI represents separate
consideration for, or is allocable to, any of their DSI
Common Stock. None of the UC Common Stock that will be
received by DSI stockholder-employees in the Merger
represents separately bargained for consideration which is
allocable to any employment agreement or arrangement. The
compensation paid to any shareholder-employees will be for
services actually rendered and will be determined by
bargaining at arm's-length.


<PAGE>


          10. There is no intercorporate indebtedness
existing between UC and DSI that was issued or acquired, or
will be settled, at a discount.

          11. DSI is not under the jurisdiction of a court
in a Title 11 or similar case within the meaning of Section
368(a)(3)(A) of the Code.

          12. The Merger Agreement and the documents
described in Section 8.06 of the Merger Agreement represent
the entire understanding of DSI and UC with respect to the
Merger.

          13. References in this letter to DSI, UC or any
subsidiary thereof shall not be considered to refer to any
DSI Benefit Plan or UC Benefit Plan (each as defined in the
Merger Agreement).


                              Diamond Shamrock, Inc.



                                By:
                                   -------------------------


<PAGE>


                                                   EXHIBIT F
                                     TO THE MERGER AGREEMENT



                       [Letterhead of]

          [5% DIAMOND SHAMROCK, INC. STOCKHOLDERS]




                                                   ___, 1996




Jones, Day, Reavis & Pogue
Metropolitan Square
1450 G Street, N.W.
Washington, D.C. 20005

Cravath, Swaine & Moore
Worldwide Plaza
825 Eighth Avenue
New York, New York 10019


Dear Sirs:

          In connection with the opinion to be delivered by
you pursuant to the Agreement and Plan of Merger (the
"Merger Agreement"), dated as of September 22, 1996, between
Ultramar Corporation, a Delaware corporation ("UC"), and
Diamond Shamrock, Inc., a Delaware corporation ("DSI" or the
"Company"), I certify, as of the date hereof, to my
knowledge and belief, after due inquiry, as follows:

          1. There is no present plan or intention on the
part of the undersigned or any trust or other entity
established or controlled by or for the benefit of the
undersigned, or any entity holding assets on behalf of the
undersigned, to sell, exchange or otherwise dispose of,
reduce the risk of loss (by short sale or otherwise) of the
holding of, enter into any contract or other arrangement
with respect to, or consent to the sale, exchange or other
disposition of (each of the foregoing, a "disposition"), any
interest in the shares of stock of UC ("UC Stock") received
in the merger contemplated by the Merger Agreement (the
"Merger") that would reduce the ownership of UC Stock by the
undersigned to a number of shares having a value, as of


<PAGE>


immediately prior to the Merger, of less than 50% of the
value of all of the shares of common stock, par value $0.01
per share, of DSI ("DSI Common Stock") and 5% Cumulative
Convertible Preferred Stock, par value $0.01 per share, of
DSI ("DSI Convertible Preferred Stock") held by the
undersigned in the aggregate as of such date. For purposes
of this representation, any "disposition" (as defined above)
of UC Stock will be treated as a reduction in ownership
thereof. For purposes of this representation, shares of DSI
Common Stock, shares of DSI Convertible Preferred Stock and
shares of UC Common Stock received in the Merger and sold,
redeemed or disposed of prior to or subsequent to the
Merger, in contemplation thereof or as part of a plan
therewith, will be considered in making this representation.

          2. Neither the undersigned nor any entity referred
to in paragraph 1 above will take any position on any
Federal, state or local income tax return, or take any other
action or reporting position, that is inconsistent with the
treatment of the Merger as a reorganization within the
meaning of Section 368(a)(1)(A) of the Internal Revenue Code
of 1986, as amended (the "Code"), or with the
representations made in this letter, unless otherwise
required pursuant to a "determination" (as defined in
Section 1313(a)(1) of the Code).



                              [DSI STOCKHOLDER]



                              ---------------------------



                                                          Exhibit 4.1


                                                       EXECUTION COPY





                             AMENDMENT dated as of September 22,
                      1996, to the Rights Agreement dated as of
                      June 25, 1992, as amended by the First
                      Amendment dated as of October 26, 1992, and
                      the Amendment dated as of May 10, 1994 (as
                      amended, the "Rights Agreement"), by ULTRAMAR
                      CORPORATION.

          Pursuant to the terms of the Rights Agreement and in
accordance with Section 26 thereof, the following actions are
hereby taken:

          Section 1. Amendments to Rights Agreement. The Rights
Agreement is hereby amended as follows:

          (a) The definition of "Acquiring Person" in Section 1
is amended by

               (i) deleting the word "or" immediately before
          "(b)" in the first sentence of such definition and
          inserting "," in its place; and

               (ii) deleting the "." at the end of clause (y)
          after the word "occur" at the end of the first sentence
          of such definition and inserting in its place ",(c)
          Diamond Shamrock, Inc. ("DSI") or any of its
          wholly-owned subsidiaries (i) solely as a result of the
          execution and delivery of (x) the Agreement and Plan of
          Merger (the "Merger Agreement"), dated as of September
          22, 1996, between the Company and DSI or (y) the Stock
          Option Agreement (the "Option Agreement"), dated as of
          September 22, 1996, between the Company, as Issuer, and
          DSI, as Grantee, or the consummation of the
          transactions contemplated by the Merger Agreement or
          the Option Agreement, or (ii) solely as a result of DSI
          or any of its wholly-owned subsidiaries being or
          becoming the Beneficial Owner of not more than 2% of
          the Common Shares then outstanding in addition to the
          Common Shares that DSI has become the Beneficial Owner
          of as a result of the execution and delivery of the
          Option Agreement but excluding for the purposes of
          determining whether such 2% limitation has been
          exceeded Common Shares that DSI would be deemed the
          Beneficial Owner of because any DSI Benefit Plan (as
          that term is defined in the Merger Agreement) is the
          Beneficial


<PAGE>


          Owner of such Common Shares as of the date of this
          Amendment, or (d) a Person (i) solely as a result of
          such Person taking an assignment or transfer of DSI's
          rights under the Option Agreement, in accordance with
          the terms thereof, or the consummation of the
          transactions contemplated thereby following any such
          assignment or transfer, or (ii) solely as a result of
          such Person being or becoming the Beneficial Owner of
          not more than 2% of the Common Shares then outstanding
          in addition to the Common Shares that such Person has
          become the Beneficial Owner of as a result of the
          assignment or transfer of the Option Agreement in
          accordance with its terms but excluding for the
          purposes of determining whether such 2% limitation has
          been exceeded Common Shares that such Person would be
          deemed the Beneficial Owner of because any employee
          benefit plan of such Person is the Beneficial Owner of
          such Common Shares as of the date of such assignment or
          transfer."

          (b) A new Section 33 is added as follows:

          "Section 33. Merger with DSI. Notwithstanding any
     provision herein to the contrary, (i) neither DSI nor any of
     its wholly-owned subsidiaries shall be considered an
     Acquiring Person under this Rights Agreement, no
     Distribution Date shall occur, and no Rights shall be
     exercisable pursuant to Section 7, Section 11 or any other
     provision hereof, (x) solely as a result of the approval,
     execution or delivery of the Merger Agreement or the Option
     Agreement or the consummation of the transactions
     contemplated by the Merger Agreement or the Option
     Agreement, or (y) solely as a result of DSI or any of its
     wholly- owned subsidiaries being or becoming the Beneficial
     Owner of not more than 2% of the Common Shares then
     outstanding in addition to the Common Shares that DSI has
     become the Beneficial Owner of as a result of the execution
     and delivery of the Option Agreement but excluding for the
     purposes of determining whether such 2% limitation has been
     exceeded Common Shares that DSI would be deemed the
     Beneficial Owner of because any DSI Benefit Plan (as that
     term is defined in the Merger Agreement) is the Beneficial
     Owner of such Common Shares as of the date of this
     Amendment, and (ii) no Person shall be considered an
     Acquiring Person under this Rights Agreement, no
     Distribution Date shall


<PAGE>


     occur, and no Rights shall be exercisable pursuant to
     Section 7, Section 11 or any other provision hereof, (x)
     solely as a result of such Person taking an assignment or
     transfer of DSI's rights under the Option agreement, in
     accordance with the terms thereof, or the consummation of
     the transactions contemplated thereby following any such
     assignment or transfer, or (y) solely as a result of such
     Person being or becoming the Beneficial Owner of not more
     than 2% of the Common Shares then outstanding in addition to
     the Common Shares that such Person has become the Beneficial
     Owner of as a result of the assignment or transfer of the
     Option Agreement in accordance with its terms but excluding
     for the purposes of determining whether such 2% limitation
     has been exceeded Common Shares that such Person would be
     deemed the beneficial Owner of because any employee benefit
     plan of such Person is the Beneficial Owner of such Common
     Shares as of the date of such assignment or transfer."

          Section 2. Full Force and Effect. Except as expressly
amended hereby, the Rights Agreement shall continue in full force
and effect in accordance with the provisions thereof on the date
hereof.

          Section 3. Governing Law. This Amendment shall be
governed by and construed in accordance with the law of the State
of Delaware applicable to contracts to be made and performed
entirely within such State.


          IN WITNESS WHEREOF, the Company has caused this
Amendment to be duly executed as of the day and year first above
written.

                                    ULTRAMAR CORPORATION,


                                    By: /s/ Patrick J. Guarino
                                       ------------------------------
                                       Name:  Patrick J. Guarino
                                       Title: Vice President, General
                                              Counsel and Secretary



                                                     Exhibit 10.1


                      STOCK OPTION AGREEMENT


          STOCK OPTION AGREEMENT, dated as of September 22, 1996
(the "Agreement"), by and between Diamond Shamrock, Inc., a
Delaware corporation ("Issuer"), and Ultramar Corporation, a
Delaware corporation ("Grantee").

                             RECITALS

          A. Issuer and Grantee have entered into an Agreement
and Plan of Merger, dated as of the date hereof (the "Merger
Agreement," capitalized terms not defined herein will have the
meanings set forth in the Merger Agreement), providing for, among
other things, the merger of Issuer with and into Grantee with
Grantee as the surviving corporation in the Merger;

          B. As a condition and inducement to Grantee's
willingness to enter into the Merger Agreement and the UC Stock
Option Agreement, Grantee has requested that Issuer agree, and
Issuer has agreed, to grant Grantee the Option (as defined
below); and

          C. As a condition and inducement to Issuer's
willingness to enter into the Merger Agreement and this
Agreement, Issuer has requested that Grantee agree, and Grantee
has agreed, to grant Issuer an option to purchase shares of
Grantee's common stock on substantially the same terms as the
Option;

          NOW, THEREFORE, in consideration of the foregoing and
the respective representations, warranties, covenants and
agreements set forth herein Issuer and Grantee agree as follows:

          1. Grant of Option. Subject to the terms and 
conditions set forth herein, Issuer hereby grants to Grantee an
irrevocable option (the "Option") to purchase up to 5,858,500 (as
adjusted as set forth herein) shares (the "Option Shares") of
Common Stock, par value $0.01 per share ("Issuer Common Stock"),
of Issuer at a purchase price of $27.55 (as adjusted as set forth
herein) per Option Share (the "Purchase Price"); provided,
however, that notwithstanding anything herein to the contrary the
number of Option Shares may not exceed the whole number of shares
(rounded down) equal to (a) $60,000,000 divided by (b) the
difference between (i) the closing price on the NYSE trading day
immediately preceding the Notice Date (as defined below) per


<PAGE>


share of Issuer Common Stock as reported on the NYSE Composite
Transaction Tape (or, if not listed on the NYSE, as reported on
any other national securities exchange or national securities
quotation system on which the Issuer Common Stock is listed or
quoted, as reported in the Wall Street Journal (Northeast
edition), or, if not reported thereby, any other authoritative
source) and (ii) the Purchase Price.

          2. Exercise of Option. (a) Grantee may exercise the
Option, in whole but not in part, at any one time after the
occurrence of any event as a result of which the Grantee is
entitled to receive the Termination Fee pursuant to Section
5.09(b) of the Merger Agreement (a "Purchase Event"); provided,
however, that (i) except as provided in the last sentence of this
Section 2(a), the Option will terminate and be of no further
force and effect upon the earliest to occur of (A) the Effective
Time, (B) 18 months after the first occurrence of a Purchase
Event, and (C) termination of the Merger Agreement in accordance
with its terms prior to the occurrence of a Purchase Event,
unless the Grantee has the right to receive a Termination Fee
following such termination upon the occurrence of certain events,
in which case the Option will not terminate until the later of
(x) six months following the time such Termination Fee becomes
payable and (y) the expiration of the period in which the Grantee
has such right to receive a Termination fee, and (ii) any
purchase of Option Shares upon exercise of the Option will be
subject to compliance with the HSR Act. Notwithstanding the
termination of the Option, Grantee will be entitled to purchase
the Option Shares if it has exercised the Option in accordance
with the terms hereof prior to the termination of the Option and
the termination of the Option will not affect any rights
hereunder which by their terms do not terminate or expire prior
to or as of such termination.

          (b) In the event that Grantee wishes to exercise the
Option, it will send to Issuer a written notice (the date of
which being herein referred to as the "Notice Date") to that
effect which notice also specifies a date not earlier than three
business days nor later than 20 business days from the Notice
Date for the closing of such purchase (the "Option Closing
Date"); provided, however, that (i) if the closing of the
purchase and sale pursuant to the Option (the "Option Closing")
cannot be consummated by reason of any applicable judgment,
decree, order, law or regulation, the period of time that
otherwise would run pursuant to this sentence will run instead
from the date on which such restriction on consummation has
expired or been terminated and (ii) without limiting the
foregoing, if prior notification to or approval of any regulatory
authority is required in connection with such purchase, Grantee
and Issuer will promptly file the required notice or application


<PAGE>


for approval and will cooperate in the expeditious filing of such
notice or application, and the period of time that otherwise
would run pursuant to this sentence will run instead from the
date on which, as the case may be, (A) any required notification
period has expired or been terminated or (B) any required
approval has been obtained, and in either event, any requisite
waiting period has expired or been terminated. The place of the
Option Closing will be at the offices of Jones, Day, Reavis &
Pogue, 599 Lexington Avenue, New York, New York, and the time of
the Option Closing will be 10:00 a.m. (Eastern Time) on the
Option Closing Date.

          3. Payment and Delivery of Certificates. (a) At the
Option Closing, Grantee will pay to Issuer in immediately
available funds by wire transfer to a bank account designated in
writing by Issuer an amount equal to the Purchase Price
multiplied by the number of Option Shares.

          (b) At the Option Closing, simultaneously with the
delivery of immediately available funds as provided in Section
3(a), Issuer will deliver to Grantee a certificate or
certificates representing the Option Shares to be purchased at
the Option Closing, which Option Shares will be free and clear of
all liens, claims, charges and encumbrances of any kind
whatsoever. If at the time of issuance of the Option Shares
pursuant to the exercise of the Option hereunder, Issuer shall
not have redeemed the DSI Rights, or shall have issued any
similar securities, then each Option Share issued pursuant to
such exercise will also represent a corresponding DSI Right or
new rights with terms substantially the same as and at least as
favorable to Grantee as are provided under the DSI Rights
Agreement or any similar agreement then in effect.

          (c) Certificates for the Option Shares delivered at the
Option Closing will have typed or printed thereon a restrictive
legend which will read substantially as follows:

     "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT
     BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
     AMENDED, AND MAY BE REOFFERED OR SOLD ONLY IF SO REGISTERED
     OR IF AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE. SUCH
     SECURITIES ARE ALSO SUBJECT TO ADDITIONAL RESTRICTIONS ON
     TRANSFER AS SET FORTH IN THE STOCK OPTION AGREEMENT, DATED
     AS OF SEPTEMBER 22, 1996, A COPY OF WHICH MAY BE OBTAINED
     FROM THE SECRETARY OF DIAMOND SHAMROCK, INC. AT ITS
     PRINCIPAL EXECUTIVE OFFICES."

It is understood and agreed that (i) the reference to
restrictions arising under the Securities Act in the above legend


<PAGE>


will be removed by delivery of substitute certificate(s) without
such reference if Grantee has delivered to Issuer a copy of a
letter from the staff of the SEC, or an opinion of counsel in
form and substance reasonably satisfactory to Issuer and its
counsel, to the effect that such legend is not required for
purposes of the Securities Act and (ii) the reference to
restrictions pursuant to this Agreement in the above legend will
be removed by delivery of substitute certificate(s) without such
reference if the Option Shares evidenced by certificate(s)
containing such reference have been sold or transferred in
compliance with the provisions of this Agreement under
circumstances that do not require the retention of such
reference.

          4. Representations and Warranties of Issuer. Issuer
hereby represents and warrants to Grantee as follows:

               (a) Due Authorization. Issuer has all requisite
     corporate power and authority to enter into this Agreement
     and to consummate the transactions contemplated hereby. The
     execution and delivery of this Agreement by Issuer and the
     consummation by Issuer of the transactions contemplated
     hereby have been duly authorized by all necessary corporate
     action on the part of Issuer. This Agreement has been duly
     executed and delivered by Issuer and constitutes a legal,
     valid, and binding obligation of Issuer, enforceable against
     Issuer in accordance with its terms.

               (b) Authorized Stock. Issuer's representations and
     warranties in Section 3.01(c) of the Merger Agreement are
     incorporated herein by reference. Without limiting the
     generality or effect of the foregoing, Issuer has taken all
     necessary corporate and other action to authorize and
     reserve and, subject to the expiration or termination of any
     required waiting period under the HSR Act, to permit it to
     issue, and, at all times from the date hereof until the
     obligation to deliver Option Shares upon the exercise of the
     Option terminates, shall have reserved for issuance, upon
     exercise of the Option, shares of Issuer Common Stock
     necessary for Grantee to exercise the Option, and Issuer
     will take all necessary corporate action to authorize and
     reserve for issuance all additional shares of Issuer Common
     Stock or other securities which may be issued pursuant to
     Section 6 upon exercise of the Option. The shares of Issuer
     Common Stock to be issued upon due exercise of the Option,
     including all additional shares of Issuer Common Stock or
     other securities which may be issuable upon exercise of the
     Option or any Substitute Option pursuant to Section 6, upon
     issuance pursuant hereto, will be duly and validly issued,
     fully paid and nonassessable, and will be delivered free and


<PAGE>


     clear of all liens, claims, charges and encumbrances of any
     kind or nature whatsoever, including without limitation any
     preemptive rights of any stockholder of Issuer.

               (c) No Conflicts. The execution and delivery of
     this Agreement does not, and the consummation of the
     transactions contemplated by this Agreement and compliance
     with the provisions of this Agreement will not, conflict
     with, or result in any violation of, or default (with or
     without notice or lapse of time or both) under, or give rise
     to a right of termination, cancellation, or acceleration of
     any obligation or loss of a material benefit under, or
     result in the creation of any Lien upon any of the
     properties or assets of Issuer or any of its Significant
     Subsidiaries under, (i) the certificate of incorporation or
     by-laws of Issuer or the comparable organizational documents
     of any Significant Subsidiary of Issuer, (ii) any loan or
     credit agreement, note, bond, mortgage, indenture, lease or
     other agreement, instrument, permit, concession, franchise,
     or license applicable to Issuer or any Significant
     Subsidiary of Issuer or their respective properties or
     assets, or (iii) subject to the expiration or termination of
     any required waiting period under the HSR Act, any judgment,
     order, decree, statute, law, ordinance, rule, or regulation
     applicable to Issuer or any of its Significant Subsidiaries
     or their respective properties or assets, other than, in the
     case of clauses (ii) and (iii), any such conflicts,
     violations, defaults, rights, losses, or Liens that
     individually or in the aggregate would not (x) have a
     material adverse effect on Issuer, (y) impair the ability of
     Issuer to perform its obligations under this Agreement or
     (z) prevent or materially delay the consummation of any of
     the transactions contemplated by this Agreement.

               (d) State Takeover Statutes. The Board of
     Directors of Issuer has approved the terms of this Agreement
     and the consummation of the transactions contemplated by
     this Agreement for the purposes of Section 203 of the DGCL.

               (e) DSI Rights Amendment. The DSI Rights Agreement
     has been amended as set forth in Section 3.01(s) of the
     Merger Agreement.

          5. Representations and Warranties of Grantee. Grantee
hereby represents and warrants to Issuer that:

               (a) Due Authorization. Grantee has all requisite
     corporate power and authority to enter into this Agreement
     and to consummate the transactions contemplated hereby. The
     execution and delivery of this Agreement by Grantee and the


<PAGE>


     consummation by Grantee of the transactions contemplated
     hereby have been duly authorized by all necessary corporate
     action on the part of Grantee. This Agreement has been duly
     executed and delivered by Grantee and constitutes a legal,
     valid, and binding obligation of Grantee, enforceable
     against Grantee in accordance with its terms.

               (b) No Conflicts. The execution and delivery of
     this Agreement does not, and the consummation of the
     transactions contemplated by this Agreement and compliance
     with the provisions of this Agreement hereby will not,
     conflict with or result in any violation of, or default
     (with or without notice or lapse of time or both) under, or
     give rise to a right of termination, cancellation, or
     acceleration of any obligation or loss of a material benefit
     under, or result in the creation of any Lien upon any of the
     properties or assets of Grantee or any of its Significant
     Subsidiaries under, (i) the certificate of incorporation or
     by-laws of Grantee or the comparable organizational
     documents of any Significant Subsidiary of Grantee, (ii) any
     loan or credit agreement, note, bond, mortgage, indenture,
     lease or other agreement, instrument, permit, concession,
     franchise, or license applicable to Grantee or any
     Significant Subsidiary of Grantee or their respective
     properties or assets, or (iii) subject to the expiration or
     termination of any required waiting period under the HSR
     Act, any judgment, order, decree, statute, law, ordinance,
     rule, or regulation applicable to Grantee or any of its
     Significant Subsidiaries or their respective properties or
     assets, other than, in the case of clauses (ii) and (iii),
     any such conflicts, violations, defaults, rights, losses, or
     Liens that individually or in the aggregate would not (x)
     have a material adverse effect on Grantee, (y) impair the
     ability of Grantee to perform its obligations under this
     Agreement or (z) prevent or materially delay the
     consummation of any of the transactions contemplated by this
     Agreement.

               (c) Purchase Not for Distribution. Any Option
     Shares or other securities acquired by Grantee upon exercise
     of the Option will not be transferred or otherwise disposed
     of except in a transaction registered, or exempt from
     registration, under the Securities Act.

          6. Adjustment upon Changes in Capitalization, Etc. (a)
In the event of any change in Issuer Common Stock by reason of a
stock dividend, split-up, merger, recapitalization, combination,
exchange of shares, or similar transaction, the type and number
of shares or securities subject to the Option, and the Purchase
Price therefor, will be adjusted appropriately, and


<PAGE>


proper provision will be made in the agreements governing such
transaction, so that Grantee will receive upon exercise of the
Option the number and class of shares or other securities or
property that Grantee would have received in respect of Issuer
Common Stock if the Option had been exercised immediately prior
to such event or the record date therefor, as applicable. Subject
to Section 1, and without limiting the parties' relative rights
and obligations under the Merger Agreement, if any additional
shares of Issuer Common Stock are issued after the date of this
Agreement (other than pursuant to an event described in the first
sentence of this Section 6(a)), the number of shares of Issuer
Common Stock subject to the Option will be adjusted so that,
after such issuance, it equals 19.9% of the number of shares of
Issuer Common Stock then issued and outstanding, without giving
effect to any shares subject to or issued pursuant to the Option.

          (b) Without limiting the parties' relative rights and
obligations under the Merger Agreement, in the event that Issuer
enters into an agreement (i) to consolidate with or merge into
any person, other than Grantee or one of its subsidiaries, and
Issuer will not be the continuing or surviving corporation in
such consolidation or merger, (ii) to permit any person, other
than Grantee or one of its subsidiaries, to merge into Issuer and
Issuer will be the continuing or surviving corporation, but in
connection with such merger, the shares of Issuer Common Stock
outstanding immediately prior to the consummation of such merger
will be changed into or exchanged for stock or other securities
of Issuer or any other person or cash or any other property, or
the shares of Issuer Common Stock outstanding immediately prior
to the consummation of such merger will, after such merger,
represent less than 50% of the outstanding voting securities of
the merged company, or (iii) to sell or otherwise transfer all or
substantially all of its assets to any person, other than Grantee
or one of its subsidiaries, then, and in each such case, the
agreement governing such transaction will make proper provision
so that the Option will, upon the consummation of any such
transaction and upon the terms and conditions set forth herein,
be converted into, or exchanged for, an option with identical
terms appropriately adjusted to acquire the number and class of
shares or other securities or property that Grantee would have
received in respect of Issuer Common Stock if the Option had been
exercised immediately prior to such consolidation, merger, sale,
or transfer, or the record date therefor, as applicable.

          (c) If, prior to the termination of the Option in
accordance with Section 2 or the Notice Date, Issuer enters into
any agreement pursuant to which all outstanding shares of Issuer
Common Stock are to be purchased for, or converted into the right
to receive, cash (a "Transaction"), Issuer covenants that proper


<PAGE>


provision will be made in such agreement to provide that, if the
Option shall not theretofore have been exercised, then upon the
closing of the Transaction (which in the case of a Transaction
involving a tender offer will be when shares of Issuer Common
Stock are accepted for payment), Grantee will receive in exchange
for the cancellation of the Option an amount in cash equal to the
Cash Consideration. For purposes of this Agreement, the term
"Cash Consideration" means the lesser of (i) $60,000,000 and (ii)
the number of Option Shares multiplied by the difference between
(A) the amount of cash per share of Issuer Common Stock to be
received by a holder of Issuer Common Stock in such Transaction
and (B) the Purchase Price.

          7. Registration Rights. Issuer will, if requested by
Grantee at any time and from time to time within three years of
the exercise of the Option, as expeditiously as possible prepare
and file up to three registration statements under the Securities
Act if such registration is necessary in order to permit the sale
or other disposition of any or all shares of securities that have
been acquired by or are issuable to Grantee upon exercise of the
Option in accordance with the intended method of sale or other
disposition stated by Grantee, including a "shelf" registration
statement under Rule 415 under the Securities Act or any
successor provision, and Issuer will use its best efforts to
qualify such shares or other securities under any applicable
state securities laws. Grantee agrees to use reasonable efforts
to cause, and to cause any underwriters of any sale or other
disposition to cause, any sale or other disposition pursuant to
such registration statement to be effected on a widely
distributed basis so that upon consummation thereof no purchaser
or transferee will own beneficially more than 4.9% of the then-
outstanding voting power of Issuer. Issuer will use reasonable
efforts to cause each such registration statement to become
effective, to obtain all consents or waivers of other parties
which are required therefor, and to keep such registration
statement effective for such period not in excess of 180 calendar
days from the day such registration statement first becomes
effective as may be reasonably necessary to effect such sale or
other disposition. The obligations of Issuer hereunder to file a
registration statement and to maintain its effectiveness may be
suspended for one or more periods of time not exceeding 60
calendar days in the aggregate if the Board of Directors of
Issuer shall have determined that the filing of such registration
statement or the maintenance of its effectiveness would require
disclosure of nonpublic information that would materially and
adversely affect Issuer. Any registration statement prepared and
filed under this Section 7, and any sale covered thereby, will be
at Issuer's expense except for underwriting discounts or
commission, brokers' fees and the fees and disbursements of
Grantee's counsel related thereto. Grantee will provide all


<PAGE>


information reasonably requested by Issuer for inclusion in any
registration statement to be filed hereunder. If, during the time
periods referred to in the first sentence of this Section 7,
Issuer effects a registration under the Securities Act of Issuer
Common Stock for its own account or for any other stockholders of
Issuer (other than on Form S-4 or Form S-8, or any successor
form), it will allow Grantee the right to participate in such
registration, and such participation will not affect the
obligation of Issuer to effect demand registration statements for
Grantee under this Section 7; provided that, if the managing
underwriters of such offering advise Issuer in writing that in
their opinion the number of shares of Issuer Common Stock
requested to be included in such registration exceeds the number
which can be sold in such offering, Issuer will include the
shares requested to be included therein by Grantee pro rata with
the shares intended to be included therein by Issuer. In
connection with any registration pursuant to this Section 7,
Issuer and Grantee will provide each other and any underwriter of
the offering with customary representations, warranties,
covenants, indemnification, and contribution in connection with
such registration.

          8. Transfers. The Option Shares may not be sold,
assigned, transferred, or otherwise disposed of except (i) in an
underwritten public offering as provided in Section 7 or (ii) to
any purchaser or transferee who would not, to the knowledge of
the Grantee after reasonable inquiry, beneficially owned more
than 4.9% of the then-outstanding voting power of the Issuer.
Nothing herein will limit or affect the right of the Grantee to
transfer or assign this Agreement as provided in Section 11(g).

          9. Listing. If Issuer Common Stock or any other
securities to be acquired upon exercise of the Option are then
listed on the NYSE (or any other national securities exchange or
national securities quotation system), Issuer, upon the request
of Grantee, will promptly file an application to list the shares
of Issuer Common Stock or other securities to be acquired upon
exercise of the Option on the NYSE (and any such other national
securities exchange or national securities quotation system) and
will use reasonable efforts to obtain approval of such listing as
promptly as practicable.

          10. Loss or Mutilation. Upon receipt by Issuer of
evidence reasonably satisfactory to it of the loss, theft,
destruction or mutilation of this Agreement, and (in the case of
loss, theft or destruction) of reasonably satisfactory
indemnification, and upon surrender and cancellation of this
Agreement, if mutilated, Issuer will execute and deliver a new
Agreement of like tenor and date. Any such new Agreement 
executed and delivered will constitute an additional contractual


<PAGE>


obligation on the part of Issuer, whether or not the Agreement so
lost, stolen, destroyed, or mutilated shall at any time be
enforceable by anyone.

          11. Miscellaneous.

          (a) Expenses. Except as otherwise provided in the
Merger Agreement, each of the parties hereto will bear and pay
all costs and expenses incurred by it or on its behalf in
connection with the transactions contemplated hereunder,
including fees and expenses of its own financial consultants,
investment bankers, accountants, and counsel.

          (b) Amendment. This Agreement may not be amended,
except by an instrument in writing signed on behalf of each of
the parties.

          (c) Extension; Waiver. Any agreement on the part of a
party to waive any provision of this Agreement, or to extend the
time for performance, will be valid only if set forth in an
instrument in writing signed on behalf of such party. The failure
of any party to this Agreement to assert any of its rights under
this Agreement or otherwise will not constitute a waiver of such
rights.

          (d) Entire Agreement; No Third-Party Beneficiaries.
This Agreement, the Merger Agreement (including the documents and
instruments referred to therein) and the Confidentiality
Agreement (i) constitute the entire agreement, and supersede all
prior agreements and understandings, both written and oral,
between the parties with respect to the subject matter of this
Agreement, and (ii) except as provided in Section 8.06 of the
Merger Agreement, are not intended to confer upon any person
other than the parties any rights or remedies.

          (e) Governing Law. This Agreement will be governed by,
and construed in accordance with, the laws of the State of
Delaware, regardless of the laws that might otherwise govern
under applicable principles of conflict of laws thereof.

          (f) Notices. All notices, requests, claims, demands,
and other communications under this Agreement must be in writing
and will be deemed given if delivered personally, telecopied
(which is confirmed), or sent by overnight courier (providing
proof of delivery) to the parties at the following addresses (or
at such other address for a party as shall be specified by like
notice):


<PAGE>


          If to Issuer to:

              Diamond Shamrock, Inc.
              9830 Colonnade Blvd.
              San Antonio, Texas  78230
              Attention:  Timothy J. Fretthold, Esq.

              Fax:  (210) 641-8885

          with a copy to:

              Jones, Day, Reavis & Pogue
              599 Lexington Avenue
              New York, New York 10022
              Attention:  Robert A. Profusek, Esq.

              Fax:  (212) 755-7306

          If to Grantee to:

              Ultramar Corporation
              Two Pickwick Plaza
              Suite 300
              Greenwich, Connecticut  06830
              Attention:  Patrick Guarino, Esq.

              Fax:  (203) 622-7007

          with a copy to:

              Cravath, Swaine & Moore
              Worldwide Plaza
              825 Eighth Avenue
              New York, New York 10019
              Attention:  William P. Rogers, Jr., Esq.

              Fax:  (212) 474-3700

          (g) Assignment. Subject to the third sentence of this
Section 11(g), neither this Agreement nor any of the rights,
interests, or obligations under this Agreement may be assigned or
delegated, in whole or in part, by operation of law or otherwise,
by Issuer or Grantee without the prior written consent of the
other. Any assignment or delegation in violation of the preceding
sentence will be void. Notwithstanding the foregoing, at any time
after the Option becomes exercisable, this Agreement, together
with any rights, interests, or obligations of Grantee hereunder,
may be transferred or assigned in its entirety by Grantee without
the consent of or any action by Issuer upon notice by Grantee to
Issuer as herein provided. Subject to the


<PAGE>


first and second sentences of this Section 11(g), this Agreement
will be binding upon, inure to the benefit of, and be enforceable
by, the parties and their respective successors and assigns.

          (h) Further Assurances. In the event of any exercise of
the Option by Grantee, Issuer and Grantee will execute and
deliver all other documents and instruments and take all other
Section that may be reasonably necessary in order to consummate
the transactions provided for by such exercise.

          (i) Enforcement. The parties agree that irreparable
damage would occur and that the parties would not have any
adequate remedy at law in the event that any of the provisions of
this Agreement were not performed in accordance with their
specific terms or were otherwise breached. It is accordingly
agreed that the parties will be entitled to an injunction or
injunctions to prevent breaches of this Agreement and to enforce
specifically the terms and provisions of this Agreement in any
federal court located in the State of Delaware or in Delaware
state court, the foregoing being in addition to any other remedy
to which they are entitled at law or in equity. In addition, each
of the parties hereto (i) consents to submit itself to the
personal jurisdiction of any federal court located in the State
of Delaware or any Delaware state court in the event any dispute
arises out of this Agreement or any of the transactions
contemplated by this Agreement, (ii) agrees that it will not
attempt to deny or defeat such personal jurisdiction by motion or
other request for leave from any such court, and (iii) agrees
that it will not bring any action relating to this Agreement or
any of the transactions contemplated by this Agreement in any
court other than a federal court sitting in the State of Delaware
or a Delaware state court.


<PAGE>


          IN WITNESS WHEREOF, Issuer and Grantee have caused this
Agreement to be signed by their respective officers thereunto
duly authorized as of the day and year first written above.

                              DIAMOND SHAMROCK, INC.


                              By: /s/ Roger R. Hemminghaus
                                  ---------------------------
                                  Roger R. Hemminghaus
                                  Chairman of the Board,
                                  Chief Executive Officer and
                                  President

                              ULTRAMAR CORPORATION


                              By: /s/ Jean Gaulin
                                  ---------------------------
                                  Jean Gaulin
                                  Chairman of the Board and
                                  Chief Executive Officer



                                                     Exhibit 10.2

                      STOCK OPTION AGREEMENT


     STOCK OPTION AGREEMENT, dated as of September 22, 1996 (the
"Agreement"), by and between Ultramar Corporation, a Delaware
corporation ("Issuer"), and Diamond Shamrock, Inc., a Delaware
corporation ("Grantee").

                             RECITALS

          A. Issuer and Grantee have entered into an Agreement
and Plan of Merger, dated as of the date hereof (the "Merger
Agreement," capitalized terms not defined herein will have the
meanings set forth in the Merger Agreement), providing for, among
other things, the merger of Grantee with and into Issuer with
Issuer as the surviving corporation in the Merger;

          B. As a condition and inducement to Grantee's
willingness to enter into the Merger Agreement and the DSI Stock
Option Agreement, Grantee has requested that Issuer agree, and
Issuer has agreed, to grant Grantee the Option (as defined
below); and

          C. As a condition and inducement to Issuer's
willingness to enter into the Merger Agreement and this
Agreement, Issuer has requested that Grantee agree, and Grantee
has agreed, to grant Issuer an option to purchase shares of
Grantee's common stock on substantially the same terms as the
Option;

          NOW, THEREFORE, in consideration of the foregoing and
the respective representations, warranties, covenants and
agreements set forth herein Issuer and Grantee agree as follows:

          1.  Grant of Option.  Subject to the terms and 
conditions set forth herein, Issuer hereby grants to Grantee an
irrevocable option (the "Option") to purchase up to 8,927,500 (as
adjusted as set forth herein) shares (the "Option Shares") of
Common Stock, par value $0.01 per share ("Issuer Common Stock"),
of Issuer at a purchase price of $27.20 (as adjusted as set forth
herein) per Option Share (the "Purchase Price"); provided,
however, that notwithstanding anything herein to the contrary the
number of Option Shares may not exceed the whole number of shares
(rounded down) equal to (a) $60,000,000 divided by (b) the
difference between (i) the closing price on the NYSE trading day
immediately preceding the Notice Date (as defined below) per
share of Issuer Common Stock as reported on the NYSE Composite
Transaction Tape (or, if not listed on the NYSE, as reported on
any other national securities exchange or national securities
quotation system on which the Issuer Common Stock is listed or
quoted, as reported in the Wall Street Journal (Northeast


<PAGE>


edition), or, if not reported thereby, any other authoritative
source) and (ii) the Purchase Price.

          2. Exercise of Option. (a) Grantee may exercise the
Option, in whole but not in part, at any one time after the
occurrence of any event as a result of which the Grantee is
entitled to receive the Termination Fee pursuant to Section
5.09(c) of the Merger Agreement (a "Purchase Event"); provided,
however, that (i) except as provided in the last sentence of this
Section 2(a), the Option will terminate and be of no further
force and effect upon the earliest to occur of (A) the Effective
Time, (B) 18 months after the first occurrence of a Purchase
Event, and (C) termination of the Merger Agreement in accordance
with its terms prior to the occurrence of a Purchase Event,
unless the Grantee has the right to receive a Termination Fee
following such termination upon the occurrence of certain events,
in which case the Option will not terminate until the later of
(x) six months following the time such Termination Fee becomes
payable and (y) the expiration of the period in which the Grantee
has such right to receive a Termination fee, and (ii) any
purchase of Option Shares upon exercise of the Option will be
subject to compliance with the HSR Act. Notwithstanding the
termination of the Option, Grantee will be entitled to purchase
the Option Shares if it has exercised the Option in accordance
with the terms hereof prior to the termination of the Option and
the termination of the Option will not affect any rights
hereunder which by their terms do not terminate or expire prior
to or as of such termination.

          (b) In the event that Grantee wishes to exercise the
Option, it will send to Issuer a written notice (the date of
which being herein referred to as the "Notice Date") to that
effect which notice also specifies a date not earlier than three
business days nor later than 20 business days from the Notice
Date for the closing of such purchase (the "Option Closing
Date"); provided, however, that (i) if the closing of the
purchase and sale pursuant to the Option (the "Option Closing")
cannot be consummated by reason of any applicable judgment,
decree, order, law or regulation, the period of time that
otherwise would run pursuant to this sentence will run instead
from the date on which such restriction on consummation has
expired or been terminated and (ii) without limiting the
foregoing, if prior notification to or approval of any regulatory
authority is required in connection with such purchase, Grantee
and Issuer will promptly file the required notice or application
for approval and will cooperate in the expeditious filing of such
notice or application, and the period of time that otherwise
would run pursuant to this sentence will run instead from the
date on which, as the case may be, (A) any required notification
period has expired or been terminated or (B) any required
approval has been obtained, and in either event, any requisite
waiting period has expired or been terminated. The place of the
Option Closing will be at the offices of Cravath, Swaine & Moore,
825 Eighth Avenue, New York, New York, and the time of the Option


<PAGE>


Closing will be 10:00 a.m. (Eastern Time) on the Option Closing
Date.

          3. Payment and Delivery of Certificates. (a) At the
Option Closing, Grantee will pay to Issuer in immediately
available funds by wire transfer to a bank account designated in
writing by Issuer an amount equal to the Purchase Price
multiplied by the number of Option Shares.

          (b) At the Option Closing, simultaneously with the
delivery of immediately available funds as provided in Section
3(a), Issuer will deliver to Grantee a certificate or
certificates representing the Option Shares to be purchased at
the Option Closing, which Option Shares will be free and clear of
all liens, claims, charges and encumbrances of any kind
whatsoever. If at the time of issuance of the Option Shares
pursuant to the exercise of the Option hereunder, Issuer shall
not have redeemed the UC Rights, or shall have issued any similar
securities, then each Option Share issued pursuant to such
exercise will also represent a corresponding UC Right or new
rights with terms substantially the same as and at least as
favorable to Grantee as are provided under the UC Rights
Agreement or any similar agreement then in effect.

          (c) Certificates for the Option Shares delivered at the
Option Closing will have typed or printed thereon a restrictive
legend which will read substantially as follows:

          "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE
          NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
          AS AMENDED, AND MAY BE REOFFERED OR SOLD ONLY IF SO
          REGISTERED OR IF AN EXEMPTION FROM SUCH REGISTRATION IS
          AVAILABLE. SUCH SECURITIES ARE ALSO SUBJECT TO
          ADDITIONAL RESTRICTIONS ON TRANSFER AS SET FORTH IN THE
          STOCK OPTION AGREEMENT, DATED AS OF SEPTEMBER 22, 1996,
          A COPY OF WHICH MAY BE OBTAINED FROM THE SECRETARY OF
          ULTRAMAR CORPORATION AT ITS PRINCIPAL EXECUTIVE
          OFFICES."

It is understood and agreed that (i) the reference to
restrictions arising under the Securities Act in the above legend
will be removed by delivery of substitute certificate(s) without
such reference if Grantee has delivered to Issuer a copy of a
letter from the staff of the SEC, or an opinion of counsel in
form and substance reasonably satisfactory to Issuer and its
counsel, to the effect that such legend is not required for
purposes of the Securities Act and (ii) the reference to
restrictions pursuant to this Agreement in the above legend will
be removed by delivery of substitute certificate(s) without such
reference if the Option Shares evidenced by certificate(s)
containing such reference have been sold or transferred in
compliance with the provisions of this Agreement under
circumstances that do not require the retention of such
reference.


<PAGE>


          4. Representations and Warranties of Issuer. Issuer
hereby represents and warrants to Grantee as follows:

               (a) Due Authorization. Issuer has all requisite
     corporate power and authority to enter into this Agreement
     and to consummate the transactions contemplated hereby. The
     execution and delivery of this Agreement by Issuer and the
     consummation by Issuer of the transactions contemplated
     hereby have been duly authorized by all necessary corporate
     action on the part of Issuer. This Agreement has been duly
     executed and delivered by Issuer and constitutes a legal,
     valid, and binding obligation of Issuer, enforceable against
     Issuer in accordance with its terms.

               (b) Authorized Stock. Issuer's representations and
     warranties in Section 3.02(c) of the Merger Agreement are
     incorporated herein by reference. Without limiting the
     generality or effect of the foregoing, Issuer has taken all
     necessary corporate and other action to authorize and
     reserve and, subject to the expiration or termination of any
     required waiting period under the HSR Act, to permit it to
     issue, and, at all times from the date hereof until the
     obligation to deliver Option Shares upon the exercise of the
     Option terminates, shall have reserved for issuance, upon
     exercise of the Option, shares of Issuer Common Stock
     necessary for Grantee to exercise the Option, and Issuer
     will take all necessary corporate action to authorize and
     reserve for issuance all additional shares of Issuer Common
     Stock or other securities which may be issued pursuant to
     Section 6 upon exercise of the Option. The shares of Issuer
     Common Stock to be issued upon due exercise of the Option,
     including all additional shares of Issuer Common Stock or
     other securities which may be issuable upon exercise of the
     Option or any Substitute Option pursuant to Section 6, upon
     issuance pursuant hereto, will be duly and validly issued,
     fully paid and nonassessable, and will be delivered free and
     clear of all liens, claims, charges and encumbrances of any
     kind or nature whatsoever, including without limitation any
     preemptive rights of any stockholder of Issuer.

               (c) No Conflicts. The execution and delivery of
     this Agreement does not, and the consummation of the
     transactions contemplated by this Agreement and compliance
     with the provisions of this Agreement will not, conflict
     with, or result in any violation of, or default (with or
     without notice or lapse of time or both) under, or give rise
     to a right of termination, cancellation, or acceleration of
     any obligation or loss of a material benefit under, or
     result in the creation of any Lien upon any of the
     properties or assets of Issuer or any of its Significant
     Subsidiaries under, (i) the certificate of incorporation or
     by-laws of Issuer or the comparable organizational documents
     of any Significant Subsidiary of Issuer, (ii) any loan or
     credit agreement, note, bond, mortgage, indenture, lease or


<PAGE>


     other agreement, instrument, permit, concession, franchise,
     or license applicable to Issuer or any Significant
     Subsidiary of Issuer or their respective properties or
     assets, or (iii) subject to the expiration or termination of
     any required waiting period under the HSR Act, any judgment,
     order, decree, statute, law, ordinance, rule, or regulation
     applicable to Issuer or any of its Significant Subsidiaries
     or their respective properties or assets, other than, in the
     case of clauses (ii) and (iii), any such conflicts,
     violations, defaults, rights, losses, or Liens that
     individually or in the aggregate would not (x) have a
     material adverse effect on Issuer, (y) impair the ability of
     Issuer to perform its obligations under this Agreement or
     (z) prevent or materially delay the consummation of any of
     the transactions contemplated by this Agreement.

               (d) State Takeover Statutes. The Board of
     Directors of Issuer has approved the terms of this Agreement
     and the consummation of the transactions contemplated by
     this Agreement for the purposes of Section 203 of the DGCL.

               (e) UC Rights Amendment. The UC Rights Agreement
     has been amended as set forth in Section 3.02(s) of the
     Merger Agreement.

          5. Representations and Warranties of Grantee. Grantee
hereby represents and warrants to Issuer that:

               (a) Due Authorization. Grantee has all requisite
     corporate power and authority to enter into this Agreement
     and to consummate the transactions contemplated hereby. The
     execution and delivery of this Agreement by Grantee and the
     consummation by Grantee of the transactions contemplated
     hereby have been duly authorized by all necessary corporate
     action on the part of Grantee. This Agreement has been duly
     executed and delivered by Grantee and constitutes a legal,
     valid, and binding obligation of Grantee, enforceable
     against Grantee in accordance with its terms.

               (b) No Conflicts. The execution and delivery of
     this Agreement does not, and the consummation of the
     transactions contemplated by this Agreement and compliance
     with the provisions of this Agreement hereby will not,
     conflict with or result in any violation of, or default
     (with or without notice or lapse of time or both) under, or
     give rise to a right of termination, cancellation, or
     acceleration of any obligation or loss of a material benefit
     under, or result in the creation of any Lien upon any of the
     properties or assets of Grantee or any of its Significant
     Subsidiaries under, (i) the certificate of incorporation or
     by-laws of Grantee or the comparable organizational
     documents of any Significant Subsidiary of Grantee, (ii) any
     loan or credit agreement, note, bond, mortgage, indenture,
     lease or other agreement, instrument, permit, concession,


<PAGE>


     franchise, or license applicable to Grantee or any
     Significant Subsidiary of Grantee or their respective
     properties or assets, or (iii) subject to the expiration or
     termination of any required waiting period under the HSR
     Act, any judgment, order, decree, statute, law, ordinance,
     rule, or regulation applicable to Grantee or any of its
     Significant Subsidiaries or their respective properties or
     assets, other than, in the case of clauses (ii) and (iii),
     any such conflicts, violations, defaults, rights, losses, or
     Liens that individually or in the aggregate would not (x)
     have a material adverse effect on Grantee, (y) impair the
     ability of Grantee to perform its obligations under this
     Agreement or (z) prevent or materially delay the
     consummation of any of the transactions contemplated by this
     Agreement.

               (c) Purchase Not for Distribution. Any Option
     Shares or other securities acquired by Grantee upon exercise
     of the Option will not be transferred or otherwise disposed
     of except in a transaction registered, or exempt from
     registration, under the Securities Act.

          6. Adjustment upon Changes in Capitalization, Etc. (a)
In the event of any change in Issuer Common Stock by reason of a
stock dividend, split-up, merger, recapitalization, combination,
exchange of shares, or similar transaction, the type and number
of shares or securities subject to the Option, and the Purchase
Price therefor, will be adjusted appropriately, and proper
provision will be made in the agreements governing such
transaction, so that Grantee will receive upon exercise of the
Option the number and class of shares or other securities or
property that Grantee would have received in respect of Issuer
Common Stock if the Option had been exercised immediately prior
to such event or the record date therefor, as applicable. Subject
to Section 1, and without limiting the parties' relative rights
and obligations under the Merger Agreement, if any additional
shares of Issuer Common Stock are issued after the date of this
Agreement (other than pursuant to an event described in the first
sentence of this Section 6(a)), the number of shares of Issuer
Common Stock subject to the Option will be adjusted so that,
after such issuance, it equals 19.9% of the number of shares of
Issuer Common Stock then issued and outstanding, without giving
effect to any shares subject to or issued pursuant to the Option.

          (b) Without limiting the parties' relative rights and
obligations under the Merger Agreement, in the event that Issuer
enters into an agreement (i) to consolidate with or merge into
any person, other than Grantee or one of its subsidiaries, and
Issuer will not be the continuing or surviving corporation in
such consolidation or merger, (ii) to permit any person, other
than Grantee or one of its subsidiaries, to merge into Issuer and
Issuer will be the continuing or surviving corporation, but in
connection with such merger, the shares of Issuer Common Stock


<PAGE>


outstanding immediately prior to the consummation of such merger
will be changed into or exchanged for stock or other securities
of Issuer or any other person or cash or any other property, or
the shares of Issuer Common Stock outstanding immediately prior
to the consummation of such merger will, after such merger,
represent less than 50% of the outstanding voting securities of
the merged company, or (iii) to sell or otherwise transfer all or
substantially all of its assets to any person, other than Grantee
or one of its subsidiaries, then, and in each such case, the
agreement governing such transaction will make proper provision
so that the Option will, upon the consummation of any such
transaction and upon the terms and conditions set forth herein,
be converted into, or exchanged for, an option with identical
terms appropriately adjusted to acquire the number and class of
shares or other securities or property that Grantee would have
received in respect of Issuer Common Stock if the Option had been
exercised immediately prior to such consolidation, merger, sale,
or transfer, or the record date therefor, as applicable.

          (c) If, prior to the termination of the Option in
accordance with Section 2 or the Notice Date, Issuer enters into
any agreement pursuant to which all outstanding shares of Issuer
Common Stock are to be purchased for, or converted into the right
to receive, cash (a "Transaction"), Issuer covenants that proper
provision will be made in such agreement to provide that, if the
Option shall not theretofore have been exercised, then upon the
closing of the Transaction (which in the case of a Transaction
involving a tender offer will be when shares of Issuer Common
Stock are accepted for payment), Grantee will receive in exchange
for the cancellation of the Option an amount in cash equal to the
Cash Consideration. For purposes of this Agreement, the term
"Cash Consideration" means the lesser of (i) $60,000,000 and (ii)
the number of Option Shares multiplied by the difference between
(A) the amount of cash per share of Issuer Common Stock to be
received by a holder of Issuer Common Stock in such Transaction
and (B) the Purchase Price.

          7. Registration Rights. Issuer will, if requested by
Grantee at any time and from time to time within three years of
the exercise of the Option, as expeditiously as possible prepare
and file up to three registration statements under the Securities
Act if such registration is necessary in order to permit the sale
or other disposition of any or all shares of securities that have
been acquired by or are issuable to Grantee upon exercise of the
Option in accordance with the intended method of sale or other
disposition stated by Grantee, including a "shelf" registration
statement under Rule 415 under the Securities Act or any
successor provision, and Issuer will use its best efforts to
qualify such shares or other securities under any applicable
state securities laws. Grantee agrees to use reasonable efforts
to cause, and to cause any underwriters of any sale or other
disposition to cause, any sale or other disposition pursuant to
such registration statement to be effected on a widely
distributed basis so that upon consummation thereof no purchaser


<PAGE>


or transferee will own beneficially more than 4.9% of the then-
outstanding voting power of Issuer. Issuer will use reasonable
efforts to cause each such registration statement to become
effective, to obtain all consents or waivers of other parties
which are required therefor, and to keep such registration
statement effective for such period not in excess of 180 calendar
days from the day such registration statement first becomes
effective as may be reasonably necessary to effect such sale or
other disposition. The obligations of Issuer hereunder to file a
registration statement and to maintain its effectiveness may be
suspended for one or more periods of time not exceeding 60
calendar days in the aggregate if the Board of Directors of
Issuer shall have determined that the filing of such registration
statement or the maintenance of its effectiveness would require
disclosure of nonpublic information that would materially and
adversely affect Issuer. Any registration statement prepared and
filed under this Section 7, and any sale covered thereby, will be
at Issuer's expense except for underwriting discounts or
commission, brokers' fees and the fees and disbursements of
Grantee's counsel related thereto. Grantee will provide all
information reasonably requested by Issuer for inclusion in any
registration statement to be filed hereunder. If, during the time
periods referred to in the first sentence of this Section 7,
Issuer effects a registration under the Securities Act of Issuer
Common Stock for its own account or for any other stockholders of
Issuer (other than on Form S-4 or Form S-8, or any successor
form), it will allow Grantee the right to participate in such
registration, and such participation will not affect the
obligation of Issuer to effect demand registration statements for
Grantee under this Section 7; provided that, if the managing
underwriters of such offering advise Issuer in writing that in
their opinion the number of shares of Issuer Common Stock
requested to be included in such registration exceeds the number
which can be sold in such offering, Issuer will include the
shares requested to be included therein by Grantee pro rata with
the shares intended to be included therein by Issuer. In
connection with any registration pursuant to this Section 7,
Issuer and Grantee will provide each other and any underwriter of
the offering with customary representations, warranties,
covenants, indemnification, and contribution in connection with
such registration.

          8. Transfers. The Option Shares may not be sold,
assigned, transferred, or otherwise disposed of except (i) in an
underwritten public offering as provided in Section 7 or (ii) to
any purchaser or transferee who would not, to the knowledge of
the Grantee after reasonable inquiry, beneficially owned more
than 4.9% of the then-outstanding voting power of the Issuer.
Nothing herein will limit or affect the right of the Grantee to
transfer or assign this Agreement as provided in Section 11(g).

          9. Listing. If Issuer Common Stock or any other
securities to be acquired upon exercise of the Option are then
listed on the NYSE (or any other national securities exchange or


<PAGE>


national securities quotation system), Issuer, upon the request
of Grantee, will promptly file an application to list the shares
of Issuer Common Stock or other securities to be acquired upon
exercise of the Option on the NYSE (and any such other national
securities exchange or national securities quotation system) and
will use reasonable efforts to obtain approval of such listing as
promptly as practicable.

          10. Loss or Mutilation. Upon receipt by Issuer of
evidence reasonably satisfactory to it of the loss, theft,
destruction or mutilation of this Agreement, and (in the case of
loss, theft or destruction) of reasonably satisfactory
indemnification, and upon surrender and cancellation of this
Agreement, if mutilated, Issuer will execute and deliver a new
Agreement of like tenor and date. Any such new Agreement executed
and delivered will constitute an additional contractual
obligation on the part of Issuer, whether or not the Agreement so
lost, stolen, destroyed, or mutilated shall at any time be
enforceable by anyone.

          11. Miscellaneous.

          (a) Expenses. Except as otherwise provided in the
Merger Agreement, each of the parties hereto will bear and pay
all costs and expenses incurred by it or on its behalf in
connection with the transactions contemplated hereunder,
including fees and expenses of its own financial consultants,
investment bankers, accountants, and counsel.

          (b) Amendment. This Agreement may not be amended,
except by an instrument in writing signed on behalf of each of
the parties.

          (c) Extension; Waiver. Any agreement on the part of a
party to waive any provision of this Agreement, or to extend the
time for performance, will be valid only if set forth in an
instrument in writing signed on behalf of such party. The failure
of any party to this Agreement to assert any of its rights under
this Agreement or otherwise will not constitute a waiver of such
rights.

          (d) Entire Agreement; No Third-Party Beneficiaries.
This Agreement, the Merger Agreement (including the documents and
instruments referred to therein) and the Confidentiality
Agreement (i) constitute the entire agreement, and supersede all
prior agreements and understandings, both written and oral,
between the parties with respect to the subject matter of this
Agreement, and (ii) except as provided in Section 8.06 of the
Merger Agreement, are not intended to confer upon any person
other than the parties any rights or remedies.

          (e) Governing Law. This Agreement will be governed by,
and construed in accordance with, the laws of the State of


<PAGE>


Delaware, regardless of the laws that might otherwise govern
under applicable principles of conflict of laws thereof.

          (f) Notices. All notices, requests, claims, demands,
and other communications under this Agreement must be in writing
and will be deemed given if delivered personally, telecopied
(which is confirmed), or sent by overnight courier (providing
proof of delivery) to the parties at the following addresses (or
at such other address for a party as shall be specified by like
notice):

          If to Issuer to:

              Ultramar Corporation
              Two Pickwick Plaza
              Suite 300
              Greenwich, Connecticut  06830
              Attention:  Patrick Guarino, Esq.

              Fax:  (203) 622-7007

          with a copy to:

              Cravath, Swaine & Moore
              Worldwide Plaza
              825 Eighth Avenue
              New York, New York 10019
              Attention:  William P. Rogers, Jr., Esq.

              Fax:  (212) 474-3700

          If to Grantee to:

              Diamond Shamrock, Inc.
              9830 Colonnade Blvd.
              San Antonio, Texas  78230
              Attention:  Timothy J. Fretthold, Esq.

              Fax:  (210) 641-8885

          with a copy to:

             Jones, Day, Reavis & Pogue
             599 Lexington Avenue
             New York, New York 10022
             Attention:  Robert A. Profusek, Esq.

             Fax:  (212) 755-7306

          (g) Assignment. Subject to the third sentence of this
Section 11(g), neither this Agreement nor any of the rights,
interests, or obligations under this Agreement may be assigned or
delegated, in whole or in part, by operation of law or otherwise,
by Issuer or Grantee without the prior written consent of the


<PAGE>


other. Any assignment or delegation in violation of the preceding
sentence will be void. Notwithstanding the foregoing, at any time
after the Option becomes exercisable, this Agreement, together
with any rights, interests, or obligations of Grantee hereunder,
may be transferred or assigned in its entirety by Grantee without
the consent of or any action by Issuer upon notice by Grantee to
Issuer as herein provided. Subject to the first and second
sentences of this Section 11(g), this Agreement will be binding
upon, inure to the benefit of, and be enforceable by, the parties
and their respective successors and assigns.

          (h) Further Assurances. In the event of any exercise of
the Option by Grantee, Issuer and Grantee will execute and
deliver all other documents and instruments and take all other
Section that may be reasonably necessary in order to consummate
the transactions provided for by such exercise.

          (i) Enforcement. The parties agree that irreparable
damage would occur and that the parties would not have any
adequate remedy at law in the event that any of the provisions of
this Agreement were not performed in accordance with their
specific terms or were otherwise breached. It is accordingly
agreed that the parties will be entitled to an injunction or
injunctions to prevent breaches of this Agreement and to enforce
specifically the terms and provisions of this Agreement in any
federal court located in the State of Delaware or in Delaware
state court, the foregoing being in addition to any other remedy
to which they are entitled at law or in equity. In addition, each
of the parties hereto (i) consents to submit itself to the
personal jurisdiction of any federal court located in the State
of Delaware or any Delaware state court in the event any dispute
arises out of this Agreement or any of the transactions
contemplated by this Agreement, (ii) agrees that it will not
attempt to deny or defeat such personal jurisdiction by motion or
other request for leave from any such court, and (iii) agrees
that it will not bring any action relating to this Agreement or
any of the transactions contemplated by this Agreement in any
court other than a federal court sitting in the State of Delaware
or a Delaware state court.


<PAGE>


          IN WITNESS WHEREOF, Issuer and Grantee have caused this
Agreement to be signed by their respective officers thereunto
duly authorized as of the day and year first written above.


                              ULTRAMAR CORPORATION


                              By: /s/ Jean Gaulin
                                  ------------------------------
                                  Jean Gaulin
                                  Chairman of the Board and
                                  Chief Executive Officer

                              DIAMOND SHAMROCK, INC.


                              By: /s/ Roger R. Hemminghaus
                                  ------------------------------
                                  Roger R. Hemminghaus
                                  Chairman of the Board,
                                  Chief Executive Officer and
                                  President



                                                       Exhibit 99.1

FOR IMMEDIATE RELEASE
- ---------------------


Contacts:   Ultramar                          Diamond Shamrock
- ---------   --------                          ----------------

            Media and Investors:              Media:  Katherine Hughes
            Steven Blank (203) 622-7019       (210) 641-8846
            For 9/23 & 9/24: (212) 953-2550   Investors:  Mary Hartman
                                              (210) 641-8840
                                              For 9/23 & 9/24: (212) 953-2550




                  ULTRAMAR AND DIAMOND SHAMROCK TO MERGE

  Merger of Equals Will Create One of the Largest North American Petroleum

                            Refiner/Marketers;

              Transaction Expected to be Accretive to Earnings


               ----------------------------------------------



GREENWICH, Conn. and SAN ANTONIO, Tex. (September 23, 1996) -- Ultramar
Corporation (NYSE:ULR) and Diamond Shamrock, Inc. (NYSE:DRM), petroleum
refining and marketing companies with strong presences in different regions
of North America, announced today that they have agreed to merge. In the
merger of equals, each share of Diamond Shamrock will be converted into
1.02 shares of Ultramar common stock. The new company will have combined
revenues of more than $8 billion and a combined equity market value of over
$2.3 billion. The transaction will be accounted for on a pooling of
interests basis and is expected to be accretive to earnings. The combined
company will be named Ultramar Diamond Shamrock Corp. and will be
headquartered in San Antonio, Texas.

     Roger Hemminghaus, chairman, chief executive officer and president of
Diamond Shamrock, will become chairman and chief executive officer of
Ultramar Diamond Shamrock. Jean Gaulin, chairman, chief executive officer
and president of Ultramar, will become the new company's vice chairman,
president and chief operating officer. Mr. Gaulin will become Ultramar
Diamond Shamrock's CEO by the end of 1998 and will become chairman within
three years thereafter. The Board of Directors will be comprised of twelve
individuals, with six each coming from the boards of Ultramar and Diamond
Shamrock.

     Ultramar Diamond Shamrock expects to pay an annual dividend of $1.10
per share of common stock, which is Ultramar's current dividend rate.

     "This is truly a merger of equals between two strong companies that
fit together remarkably well," said Mr. Hemminghaus. "By joining together,
we will leverage both our companies' considerable strength in petroleum
refining and marketing and create new opportunities for cost savings and
strategic expansion. The merger will position the new company for greater
penetration of attractive western U.S. markets, including Arizona,
California and Nevada."

     "This is a combination of two companies which have high quality assets
and management. We will be building a new company with the best management
and business opportunities from both sides. Our corporate cultures are
complementary and we are all looking forward to working together,"
Mr. Hemminghaus said.




<PAGE>





                                   - 2 -


     "Ultramar and Diamond Shamrock are ideal partners," said Mr. Gaulin.
"Diamond Shamrock's large retail network and significant presence in the
U.S. Southwest strongly complement Ultramar's refining and marketing
operations in California and Canada. With such strong regional anchors, our
new company has tremendous potential to expand into new markets and improve
performance in existing ones."

     "This merger creates exciting opportunities for the shareholders of
both companies," Mr. Gaulin said. "The transaction is expected to be
accretive to earnings. Ultramar Diamond Shamrock will benefit from enhanced
earnings growth prospects, less earnings volatility, increased geographic
diversity of revenues, and significant merger savings."

     Cost savings related to the merger are projected to be at least
$75 million annually, based primarily on the realization of operating
synergies and reduction of overhead and administrative costs, with
$25 million estimated to be realized in 1997 and the full $75 million to be
realized each year thereafter. One-time transaction costs are estimated at
$17 million, which will be booked in 1996. In addition there are
approximately $50 million in transition costs, most of which will be booked
in 1996. It is anticipated that approximately 200 positions will be
eliminated as a result of the merger, out of a combined workforce of about
17,000 employees.

     The Boards of Directors of both Ultramar and Diamond Shamrock have
approved the merger. The transaction is subject to approval by the
shareholders of both companies, and to customary regulatory approvals. The
parties expect the transaction to close at the end of this year.

     Wasserstein Perella & Co., Inc. acted as financial adviser to Diamond
Shamrock and provided a fairness opinion. Merrill Lynch & Co. acted as
principal financial adviser to Ultramar and provided a fairness opinion.

     Ultramar Corporation, headquartered in Greenwich, Connecticut, is a
petroleum refining and marketing company which operates in California,
Eastern Canada and the northeast United States. Ultramar employs
approximately 4,000 people. Ultramar operates two refineries, in
Wilmington, California, and in Quebec Province, with a combined capacity of
250,000 barrels per day. In California, it markets gasoline through
360 locations (150 owned and operated by the company) under the Ultramar
and Beacon brands. Ultramar's Eastern Canadian retail network includes
1,400 locations (of which approximately 630 are company-owned or controlled
under long-term lease). In Eastern Canada, Ultramar markets gasoline under
the Ultramar and Sergaz brands. Within this network, Ultramar owns and
operates 110 convenience stores and plans to grow this number significantly
over the next several years. Ultramar is one of the largest home heating
oil companies in North America and sells heating oil to over
175,000 households in Eastern Canada and New England.


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<PAGE>


                                   - 3 -



     Diamond Shamrock, Inc., headquartered in San Antonio, is a leading
refiner and marketer of petroleum products in the Southwest, with a growing
mix of related businesses. Diamond Shamrock has two Texas refineries with a
combined capacity of 225,000 barrels per day, and markets gasoline and
convenience store items through approximately 2,700 Corner Store, Stop N Go
and Diamond Shamrock locations (1,500 owned and operated by the company) in
nine states. Diamond Shamrock markets the largest-selling gasoline brand in
Texas and the second largest in Colorado and New Mexico. Its revenue from
convenience store merchandise approaches $1 billion annually. Diamond
Shamrock also produces petrochemical feedstocks and operates the world's
largest commercial natural gas liquids storage facility, serving the
refining and petrochemicals industries in the Texas Gulf Coast area.
Diamond Shamrock has more than 13,000 employees.


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