[Bounty__Hunter]

The AMC20 has the weak 2-piece axleshaft design that often spins the splines at the hub, leaving you stranded. If your gears are okay (you mentioned gear whine or other noise) consider upgrading to 1piece shafts as well.

The Ford 8.8 from an Explorer would be a good swap as they come in 4.10 and with a limited slip diff in many applications. I would have the axleshafts and rotors redrilled to match your 5x5.5" lug pattern (the 8.8 is 5x4.5").

Consider a 4.0L HO head when you do the rebuild, you'll make a lot more power. Better head to sink money into as well.

Then there's the 4.6L stroker using a 4.0L block and 258 crank, but how wild do you wanna get?