the pre molded aft seal sleeve 20 may be described as having an outwardly flanged first portion 24 a constantly decreasing diameter second portion 26 and an inwardly flanged third portion 28 the first portion 24 integrally connects a flange edge 30 with the second portion 26 the second portion 26 integrally connects the first portion 24 with the third portion 28 the flange edge 30 is circular about the axial centerline 22 and has a diameter 32 from about 3 7 to about 4 1 inches preferably diameter 32 is from about 3 8 to about 4 0 inches more preferably diameter 32 is from about 3 95 to about 3 98 inches in the alternative the flange edge 30 preferably has diameter 32 approximately equal to the conventional aft seal sleeves 12 the first portion 24 outwardly flanges with a radius of curvature 34 from about 1 inch to 2 inches preferably the radius of curvature 34 is from about 1 1 to 1 4 inches more preferably the radius of curvature 34 is from about 1 20 to 1 25 inches alternately the first portion 24 outwardly flanges with a radius of curvature approximately equal to the conventional aft seal sleeves 12 the second portion 26 has a constantly decreasing diameter having no radius of curvature from the first portion 24 to the third portion 28 the third portion 28 is an inwardly flanged cylinder integrally connected to the second portion 26 at a location 36 the location 36 connects the second portion 26 and the third portion 28 and has a radius of curvature 38 from about 0 01 inch to about.