Okay so I have a 1973 Duster that had a 7 1/4 rear end that measured 51.4 inches outside flange to outside flange. I found an A body 8 3/4 housing on craigslist then found an A body 8 3/4 3.55 posi center section and A-body 8 3/4 axles. I bought them both and put them together. (this was before...