Car was originally equipped with /6 and a 7 1/4 rear according to VIN. Knucklehead I bought it from swapped in v8 k frame and put a 318 with 727 in and used original driveshaft. Needless to say rear failed and he swapped in 8 1/4 rear. I got car , changed motors, blew trans and rear several times. Bought an SMR 727 then picked up an 8 3/4 that I was told came from a 67 b-body that is only an inch wider than a-body width, and spring perches are 1/2 inch wider. And i am guessing the u-joints are original size from 7 1/4....? I am unsure and everything about this car has been a nightmare. I learned the hardway about building Mopars and fast cars, so please don't beat me up to bad.