i have forgotten more than i know where i have gotten older and been off the scene a while.but are there three lengths on the tail shaft? 1 mustang,2 fairlane and comet.3 galaxie,or are they just two. i had a friend tell me the mustang and 66-67 comet were the same,i told him i thought the fairlane tail shaft was longer.i dont know for sure but im getting ready to change my 428 comet back to a 4 speed,its now a c6 but it came with a 4 speed and i found a mustang big shaft,close ratio and im wondering if it will fit my 66 comet,if not could i swap the tail shaft if they are different or should i just try to find a fairlane trans?