Percentages of Original Class Principal (or Class Notional) Balances and Weighted Average Lives Security Group 1 PSA Prepayment Assumption Rates Class AT Class AX Classes FA and S Class GY Distribution Date 0% 100% 250% 300% 500% 0% 100% 250% 300% 500% 0% 100% 250% 300% 500% 0% 100% 250% 300% 500% Initial Percent ..................    100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 May 2008  .......................... 99 99 94 94 90 100 100 100 100 100 99 97 95 94 91 100 100 94 91 83 May 2009  .......................... 99 99 76 69 38 100 100 100 100 100 98 92 85 82 73 100 100 78 71 43 May 2010  .......................... 98 98 52 38 0 100 100 100 100 0 97 86 71 67 51 100 100 59 46 0 May 2011  .......................... 97 97 34 16 0 100 100 100 100 0 96 80 60 54 35 100 100 44 28 0 May 2012  .......................... 96 96 21 0 0 100 100 100 100 0 95 74 50 44 24 100 100 33 15 0 May 2013  .......................... 95 95 13 0 0 100 100 100 0 0 93 68 42 35 17 100 100 25 6 0 May 2014  .......................... 94 94 7 0 0 100 100 100 0 0 92 63 35 28 11 100 100 21 2 0 May 2015  .......................... 93 93 4 0 0 100 100 100 0 0 90 58 29 23 8 100 100 18 0 0 May 2016  .......................... 92 92 2 0 0 100 100 100 0 0 89 53 24 18 5 100 100 17 0 0 May 2017  .......................... 91 91 0 0 0 100 100 77 0 0 87 49 20 15 4 100 97 16 0 0 May 2018  .......................... 89 89 0 0 0 100 100 20 0 0 85 45 17 12 2 100 94 14 0 0 May 2019  .......................... 88 88 0 0 0 100 100 0 0 0 83 41 14 9 2 100 90 13 0 0 May 2020  .......................... 87 87 0 0 0 100 100 0 0 0 80 37 11 7 1 100 85 11 0 0 May 2021  .......................... 85 78 0 0 0 100 100 0 0 0 78 34 9 6 1 100 80 10 0 0 May 2022  .......................... 84 69 0 0 0 100 100 0 0 0 75 31 8 5 1 100 74 8 0 0 May 2023  .......................... 82 59 0 0 0 100 100 0 0 0 73 28 6 4 0 100 68 7 0 0 May 2024  .......................... 80 49 0 0 0 100 100 0 0 0 70 25 5 3 0 100 62 6 0 0 May 2025  .......................... 79 39 0 0 0 100 100 0 0 0 66 22 4 2 0 100 56 5 0 0 May 2026  .......................... 77 29 0 0 0 100 100 0 0 0 63 19 3 2 0 100 51 4 0 0 May 2027  .......................... 75 19 0 0 0 100 100 0 0 0 59 17 3 1 0 100 45 4 0 0 May 2028  .......................... 73 10 0 0 0 100 100 0 0 0 55 15 2 1 0 100 40 3 0 0 May 2029  .......................... 70 0 0 0 0 100 100 0 0 0 50 13 2 1 0 100 34 2 0 0 May 2030  .......................... 68 0 0 0 0 100 0 0 0 0 46 11 1 1 0 100 29 2 0 0 May 2031  .......................... 65 0 0 0 0 100 0 0 0 0 40 9 1 0 0 100 24 1 0 0 May 2032  .......................... 63 0 0 0 0 100 0 0 0 0 35 7 1 0 0 99 20 1 0 0 May 2033  .......................... 56 0 0 0 0 100 0 0 0 0 29 6 0 0 0 82 15 1 0 0 May 2034  .......................... 28 0 0 0 0 100 0 0 0 0 22 4 0 0 0 64 11 1 0 0 May 2035  .......................... 0 0 0 0 0 47 0 0 0 0 16 2 0 0 0 44 7 0 0 0 May 2036  .......................... 0 0 0 0 0 0 0 0 0 0 8 1 0 0 0 23 3 0 0 0 May 2037  .......................... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Weighted Average Life (years)  ..................   22.5    16.2 3.5 2.7 1.8 28.0 22.3 10.5 5.3 2.7 20.2 11.4 6.5 5.7 3.8 27.6 19.4 5.5 3.1 1.8 PSA Prepayment Assumption Rates Class PM Class PN Classes TA, TI, TO and TX Class TJ Distribution Date 0% 100% 250% 300% 500% 0% 100% 250% 300% 500% 0% 100% 250% 300% 500% 0% 100% 250% 300% 500% Initial Percent ..................    100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 May 2008  .......................... 98 96 96 96 96 100 100 100 100 100 100 100 96 94 83 100 100 100 100 100 May 2009  .......................... 97 87 87 87 87 100 100 100 100 100 100 100 80 72 38 100 100 100 100 100 May 2010  .......................... 95 76 76 76 76 100 100 100 100 100 99 99 61 45 0 100 100 100 100 0 May 2011  .......................... 93 65 65 65 49 100 100 100 100 100 99 99 46 26 0 100 100 100 100 0 May 2012  .......................... 91 55 55 55 31 100 100 100 100 100 99 99 35 13 0 100 100 100 100 0 May 2013  .......................... 89 46 46 46 18 100 100 100 100 100 99 99 28 5 0 100 100 100 100 0 May 2014  .......................... 86 37 37 37 10 100 100 100 100 100 99 99 24 1 0 100 100 100 100 0 May 2015  .......................... 84 29 29 29 4 100 100 100 100 100 98 98 22 0 0 100 100 9 9 0 May 2016  .......................... 81 21 21 21 0 100 100 100 100 94 98 98 20 0 0 100 100 0 0 0 May 2017  .......................... 78 15 15 15 0 100 100 100 100 64 98 98 19 0 0 100 100 0 0 0 May 2018  .......................... 74 10 10 10 0 100 100 100 100 44 98 98 17 0 0 100 100 0 0 0 May 2019  .......................... 71 6 6 6 0 100 100 100 100 30 97 97 15 0 0 100 100 0 0 0 May 2020  .......................... 67 3 3 3 0 100 100 100 100 20 97 97 14 0 0 100 26 0 0 0 May 2021  .......................... 63 0 0 0 0 100 100 100 100 14 97 90 12 0 0 100 0 0 0 0 May 2022  .......................... 59 0 0 0 0 100 81 81 81 9 96 83 10 0 0 100 0 0 0 0 May 2023  .......................... 54 0 0 0 0 100 64 64 64 6 96 76 9 0 0 100 0 0 0 0 May 2024  .......................... 49 0 0 0 0 100 50 50 50 4 95 68 8 0 0 100 0 0 0 0 May 2025  .......................... 43 0 0 0 0 100 39 39 39 3 95 61 6 0 0 100 0 0 0 0 May 2026  .......................... 37 0 0 0 0 100 30 30 30 2 95 53 5 0 0 100 0 0 0 0 May 2027  .......................... 31 0 0 0 0 100 23 23 23 1 94 46 4 0 0 100 0 0 0 0 May 2028  .......................... 24 0 0 0 0 100 17 17 17 1 94 39 4 0 0 100 0 0 0 0 May 2029  .......................... 16 0 0 0 0 100 13 13 13 0 93 32 3 0 0 100 0 0 0 0 May 2030  .......................... 8 0 0 0 0 100 10 10 10 0 93 25 2 0 0 100 0 0 0 0 May 2031  .......................... 0 0 0 0 0 94 7 7 7 0 92 19 2 0 0 100 0 0 0 0 May 2032  .......................... 0 0 0 0 0 5 5 5 5 0 91 12 1 0 0 100 0 0 0 0 May 2033  .......................... 0 0 0 0 0 3 3 3 3 0 87 6 1 0 0 0 0 0 0 0 May 2034  .......................... 0 0 0 0 0 2 2 2 2 0 65 0 1 0 0 0 0 0 0 0 May 2035  .......................... 0 0 0 0 0 1 1 1 1 0 40 0 0 0 0 0 0 0 0 0 May 2036  .......................... 0 0 0 0 0 0 0 0 0 0 13 0 0 0 0 0 0 0 0 0 May 2037  .......................... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Weighted Average Life (years)  ..................   15.4 6.0 6.0 6.0 4.2 24.6 18.0 18.0 18.0 11.4 26.7 19.4 6.0 3.1 1.7 25.8 13.0 7.6 7.6 3.0 S-21