<PAGE>
Filed under Rule 424 (b) (3)
File No. 333-63153
SUPPLEMENT NO. 21 TO PROSPECTUS DATED SEPTEMBER 21, 1998
(AS SUPPLEMENTED SEPTEMBER 21, 1998)
PACCAR FINANCIAL CORP.
MEDIUM-TERM NOTES, SERIES I
DUE NINE MONTHS OR MORE FROM DATE OF ISSUE
INTEREST PAYABLE EACH MARCH 15 AND SEPTEMBER 15 AND AT MATURITY
<TABLE>
<CAPTION>
INTEREST RATE
RANGE OF MATURITIES PER ANNUM
- ------------------- ---------
<S> <C>
More than 46 months to 49 months............................... 6.92%
</TABLE>
Dated: August 18, 1999
Form of Note (check one): Book Entry [X]
Certificated [ ]
In some instances, one or more of the Agents have purchased the Notes as
principal and may resell the Notes at prices to be determined by such Agents
at the time of resale.
