The 904 went to a 2.71 low gear set in the '80's, about the same time as going to lock-up converters. Otherwise, all 727 and 904's all had a 2.45 low gear. You can swap it into an older, non-lock-up trans, but you have to know which parts to swap as a set.
Just a shift kit will help prolong the life of any OEM trans, as well as an extra cooler. Built right, both take a lot of abuse. I run a 904 in my race car.
