Dana 60 with upgraded slant six
Get one from a truck (MY 88 D350 has a Dana 60) Have it cut down,install axle ends, brakes, new axles,spring pads.Also add in a sure grip, gear set,bearings,gaskets and seals. You will be good to go. OR order a S60 from Moser or Strange for the same money. I would price it both ways to see what would cost less.