So the rear end is the last piece of the drive train left to do. I had been thinking of a 3.55 posi for a while and just now started checking details. Currently have a 2.78 so it will need a different carrier, what is the easiest/cheapest way to get hold of one?

From my previous junkyard cruises there aren't to many first gens sitting around in them, would it be easier to just pull the whole rear end from like a 70+ bird/bonni/grand prix, then swap the internals to correct ratio/posi? Would there be any fitting issues there?