This is not mine. But, if anyone is building a period correct trifive gasser this is the rear end to have. It bolts right in to a trifive.

1957 Pontiac rear end/axle assy - auto parts - by owner - vehicle...

1957 Pontiac rear end- housing, axles, 3rd member for sale. I just removed it from one of my 1957 Chieftains. It is the last '57 rear I have to sell. It is out of an original/stock Pontiac. Great...
phoenix.craigslist.org

Gordy