I have a complete rear from a '65 Starfire that I've been tripping over in my garage for far too long. This is a Pontiac 10-bolt cover/12-bolt carrier unit with 3.23 gears and positraction. The housing is very rusty, so if you already have the same rear in your 88 or 98, the interior parts would make a great conversion. Otherwise I guess you could blast it and use the entire housing, but it would never look great due to severe rust pitting. Will bolt into any 65-70 big car, but obviously if you don't already have the Pontiac rear you might have to make driveshaft alterations.
Looking for $400 complete, you pick up in Buffalo, NY.
Might be able to bring it to spring Carlisle for pick up if needed.

 

Still available for delivery to spring Carlisle.