8 1/4 rear axle

The carrier is the part that can not use anything higher than a 2.94 gear. But seeing as you want to put a sure grip in it you will have no problem. I did the same swap in my 72 dart. Somone just gave me a 8 1/4 that apperently came out of a 74 dart (had 11in drums for some reason) and I put a 3.55 sure grip in it no problem. Just make sure you are buying the parts for the right year, after 1990 (I belive) the 8 1/4s went to 28 splines from 27.