•   According to the terms of the Ginnie Mae Guaranty, Ginnie Mae will guarantee payment in full of the Class Principal Balance of each Class of Securities no later than its Final Distribution Date. Modeling Assumptions Unless otherwise indicated, the tables that follow have been prepared on the basis of the characteristics of the Underlying SMBS Securities and the following assumptions (the "Model- ing Assumptions"), among others: 1.  The Mortgage Loans underlying the Group 2, 3 and 4 Trust Assets have the assumed characteristics shown under "Assumed Characteristics of the Mortgage Loans Underlying the Group 2, 3 and 4 Trust Assets" in the Terms Sheet, except in the case of information set forth under the 0% PSA Prepayment Assumption Rate, for which each Mortgage Loan underlying a Group 2, 3 and 4 Trust Asset is assumed to have an original and a remaining term to maturity of 360 months and a Mortgage Rate of 1.50% per annum higher than the related Certificate Rate. 2.  The  Mortgage  Loans  prepay  at  the  constant  percentages  of  PSA  (described  below) shown in the related table. 3.  Distributions  on  the  Securities  are  always  received  on  the  20th  day  of  the  month, whether or not a Business Day, commencing in July 2005. 4.  A termination of the Trust does not occur. 5.  The Closing Date for the Securities is June 30, 2005. 6.  No expenses or fees are paid by the Trust other than the Trustee Fee. 7.  Distributions on the Underlying SMBS Securities are made as described in the Underly- ing SMBS Security Disclosure Document. 8.  Each Class is held from the Closing Date and is not exchanged in whole or in part. When  reading  the  tables  and  the  related  text,  investors  should  bear  in  mind  that  the Modeling Assumptions, like any other stated assumptions, are unlikely to be entirely consistent with actual experience. •   For example, most of the Mortgage Loans will not have the characteristics assumed, many Distribution Dates will occur on a Business Day after the 20th of the month, and the Trustee may cause a termination of the Trust as described under "Description of the Securities – Termination" in this Supplement. •   In addition, distributions on the Securities are based on Certificate Factors and Calcu- lated Certificate Factors, if applicable, which may not reflect actual receipts on the Trust Assets. See "Description of the Securities – Distributions" in the Base Offering Circular. Decrement Tables Prepayments  of  mortgage  loans  are  commonly  measured  by  a  prepayment  standard  or model. The model used in this Supplement ("PSA") is the standard prepayment assumption model of The Bond Market Association. PSA represents an assumed rate of prepayment each month relative to the then outstanding principal balance of the Mortgage Loans to which the model is applied. See "Yield, Maturity and Prepayment Considerations – Standard Prepay- ment Assumption Models" in the Base Offering Circular. S-20