<PAGE>
Filed under Rule 424(b)(3)
File No. 333-63153
SUPPLEMENT NO. 1 TO PROSPECTUS DATED SEPTEMBER 21, 1998
(AS SUPPLEMENTED SEPTEMBER 21, 1998)
PACCAR FINANCIAL CORP.
MEDIUM-TERM NOTES, SERIES I
PRINCIPAL AMOUNT: $45,000,000
ORIGINAL ISSUE DATE: 9/28/98
MATURITY DATE: 9/28/99
INITIAL INTEREST RATE: To be Determined
INTEREST RATE INDEX: 1-Month Libor
SPREAD: Minus 7.5 Basis Points
INDEX SOURCE: Telerate page 3750
INDEX RESET FREQUENCY: Monthly (28th of each month)
INTEREST PAYMENT PERIOD: Monthly (28th of each month)
INTEREST PAYMENT DATES: 28th of Each Month Subject to Modified Business
Day Convention as Defined by ISDA
ISSUE PRICE: 100.00%
PROCEEDS TO COMPANY: $45,000,000
UNDERWRITERS DISCOUNT: 0.00%
DAY COUNT CONVENTION: Actual/360
FORM OF NOTE (CHECK ONE): Book-Entry [X]
Certificate [ ]
AGENT/UNDERWRITER: Morgan Stanley & Co. Incorporated
DATED: SEPTEMBER 23, 1998
The Underwriter, Morgan Stanley & Co. Incorporated, has purchased the Notes
as principal and may resell the Notes at prices to be determined by such
Underwriter at the time of resale.