<PAGE>
[Letterhead of Cahill Gordon & Reindel]
July 18, 2000
(212) 701-3000
Prudential Securities Incorporated
One Seaport Plaza
New York, New York 10292
Re: Government Securities
Equity Trust Series 10
Gentlemen:
We have acted as special counsel for you as Depositor of the
Government Securities Equity Trust Series 10 (the "Trust"), in connection with
the issuance under the Trust Indenture and Agreement, dated July 18, 2000, and
related Reference Trust Agreement, dated July 18, 2000 (such Trust Indenture and
Agreement and Reference Trust Agreement collectively referred to as the
"Indenture"), among you, as Depositor, The Bank of New York, as Trustee, and
Kenny Information Systems, Inc., as Evaluator, of units of fractional undivided
interest in said Trust (the "Units") comprising the Units of Government
Securities Equity Trust Series 10. In rendering our opinion expressed below, we
have relied in part upon the opinions and representations of your officers and
upon opinions of counsel to Prudential Securities Incorporated.
Based upon the foregoing, we advise you that, in our opinion,
when the Indenture has been duly executed and delivered on behalf of the
Depositor and the Trustee and when the Receipt for Units evidencing the Units
has been duly executed and delivered by the Depositor and the Trustee in
accordance with the Indenture, the Units will be legally issued, fully paid and
nonassessable by the Trust, and will constitute valid and binding obligations of
the Trust and the Depositor in accordance with their terms,
<PAGE>
2
except that enforceability of certain provisions thereof may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or other similar
laws affecting creditors generally and by general equitable principles.
We hereby consent to the filing of this opinion as an exhibit
to the Registration Statement (File No. 333-38826) relating to the Units
referred to above and to the use of our name and to the reference to our firm in
said Registration Statement and the related Prospectus.
Very truly yours,
Cahill Gordon & Reindel
