Each PAC and TAC Class exhibits an Effective Range or Rate of constant prepayment rates at which such Class will receive Scheduled Payments. That range or rate may differ from the Structuring Range or Rate used to create the related principal balance schedule. Based on the Modeling Assumptions, the initial Effective Ranges or Rate for the PAC and TAC Classes are as follows: Initial Effective Ranges PAC I Classes FM and PO (in the aggregate)...................................... 100% PSA through 350% PSA PAC II Classes TG, TK and TL (in the aggregate) .............................. 140% PSA through 372% PSA Initial Effective Rate TAC Classes YC and YD (in the aggregate)...................................... 235% PSA •   The principal payment stability of the PAC I Classes will be supported by the related PAC II and Support Classes. •   The principal payment stability of the PAC II Classes will be supported by the related Support Classes. •   The principal payment stability of the TAC Classes will be supported by the related Support Class. If all of the Classes supporting a given Class are retired before the Class being supported is retired, the outstanding Class will no longer have an Effective Range or Rate and will become more sensitive to prepayments on the related Mortgage Loans. There is no assurance that the related Mortgage Loans will have the characteristics assumed in the Modeling Assumptions, which were used to determine the initial Effective Ranges or Rate. If the initial Effective Ranges or Rate were calculated using the actual characteristics of the related Mortgage Loans, the initial Effective Ranges or Rate could differ from those shown in the above tables or an initial Effective Rate might not exist. Therefore, even if the Mortgage Loans  were  to  prepay  at  a  constant  rate  within  the  initial  Effective  Range  or  at  the  initial Effective Rate shown for any Class in the above tables, that Class could fail to receive Scheduled Payments. Moreover, the Mortgage Loans will not prepay at any constant rate. Non-constant prepay- ment  rates  can  cause  any  PAC  or  TAC  Class  not  to  receive  Scheduled  Payments,  even  if prepayment rates remain within the initial Effective Range (or if prepayment rates average the Effective Rate), if any, for that Class. Further, the Effective Range for any PAC Class can narrow, shift over time or cease to exist and the Effective Rate for any TAC Class can change or cease to exist depending on the actual characteristics of the related Mortgage Loans. If the related Mortgage Loans prepay at rates that are generally below the Effective Range or Rate for any PAC or TAC Class, the amount available to pay principal on the Securities may be insufficient  to  produce  Scheduled  Payments  on  such  related  PAC  or  TAC  Class,  and  its Weighted Average Life may be extended, perhaps significantly. If the related Mortgage Loans prepay at rates that are generally above the Effective Range or Rate for any PAC or TAC Class, its supporting Classes may be retired earlier than that PAC or TAC Class, and its Weighted Average Life may be shortened, perhaps significantly. S-17