Assumed Characteristics of the Mortgage Loans Underlying the Group 1, 2, 3 and 4 Trust Assets1: Principal Balance2 Weighted Average Remaining Term to Maturity (in months) Weighted Average Loan Age (in months) Weighted Average Mortgage Rate3 Group 1 Trust Assets $500,000,000 357 2 6.30% Group 2 Trust Assets $150,000,000 351 1 6.25% Group 3 Trust Assets $277,065,532 358 1 6.00% Group 4 Trust Assets $100,000,000 358 1 5.80% 1As of May 1, 2003. 2Does not include Group 3 Trust Assets that will be added to pay the Trustee Fee. 3The Mortgage Loans underlying the Group 1 and 4 Trust Assets may bear interest at rates ranging from 0.5% to 1.5% per annum above the related Certificate Rate. The actual remaining terms to maturity, loan ages and, in the case of the Group 1 and 4 Trust Assets, Mortgage Rates of many of the Mortgage Loans underlying the Group 1, 2, 3 and 4 Trust Assets will differ from the weighted averages shown above, perhaps significantly. See "The Trust Assets – The Mortgage Loans" in this Supplement. See Exhibit A to this Supplement for certain information regarding the characteristics of the Mortgage Loans included in the Underlying Trust. Issuance of Securities: The Securities, other than the Residual Securities, will initially be issued in book-entry form through the book-entry system of the U.S. Federal Reserve Banks (the "Fedwire  Book-Entry  System").  The  Residual  Securities  will  be  issued  in  fully  registered, certificated form. See "Description of the Securities – Form of Securities" in this Supplement. Modification  and  Exchange:  If  you  own  exchangeable  Securities  you  will  be  able,  upon notice and payment of an exchange fee, to exchange them for a proportionate interest in the related Securities shown on Schedule I to this Supplement. See "Description of the Securi- ties – Modification and Exchange" in this Supplement. Increased Minimum Denomination Classes: Each Class that constitutes a Principal Only, Interest Only or Non-Sticky Jump Class. See "Description of the Securities – Form of Securi- ties" in this Supplement. Interest Rates: The Interest Rates for the Fixed Rate Classes are shown on the inside cover page of this Supplement or on Schedule I to this Supplement. B-11