being that year you have a 26 spline axleshaft and there is 2 different carrier's for different ratio's. What ratio are you looking to run?
bb71mopar has a junk monte ss that he was thinking of removing the axle from. not sure how good the diff is though
PM mikesfastss, he has an 8.5 Grand National rear end.
450 takes it obo it does need a ring and pinion though or I have a 7.5 out of a monte ss ill sell for 350 painted with chrome cover.