If you want an inexpensive option, scour the junkyards for a 2.5L equipped XJ with a 5spd, chances are you can nab the 4.10 rear axle. Another good option is the rear axle from a '95+ Ford Explorer, they can be found with 4.10 gears, have disc brakes, and same wheel lug pattern as the Cherokee. They can also be found with a limited slip differential, watch for the 4L10 tag bolted to the diff cover.