So what am I missing? Why would you do all that work to use a FORD 8.8 when you could find an 8 3/4 Mopar the right width and drop it in - probably even find a stock driveshaft that fits... Just sayin'
Well, part of my reasoning is right there in your question (not to come across rude): I could find a 8-3/4 that would drop right. It's possible yes, but in my neck of the country, 8-3/4 rears are rare and those from an A-body are rarer still.
For instance, the only 8-3/4 that I'm currently aware of for sale "close" to me in California is currently bolted into a 65 Belvedere that is about 4 hours away from me. The seller wants $500 and I have to pull the axle myself. Then, because it's a B-body rear, I would have to have both axle tubes shortened and source shorter axle shafts or have them made.
I can go to a local Pick n Pull yard on a half price weekend, find my donor car and walk out with a Ford 8.8 guaranteed for under $200. I work at a heavy equipment manufacturer and I can have one of our welders cut and weld the axle tube on one side.
