For a good, inexpensive axle upgrade, scour the junk yards for a 4-cyl. Comanche(preferably), Cherokee, or a Ford explorer with rear disc brakes. you have to research the Ford to find the right gear set(4.10), but all the 4-cyl XJ/MJs came with 4.10 gears(or very rarely lower) That'll get some power back. Both the Cherokee and Ford axles would require welding spring perches on to bolt under the Comanche, and the Ford would require modification to make the brakes work, but the Ford 8.8 rear axle is a great upgrade.
You can do a inexpensive "budget boost" lift and get it up a couple inches for under $100.00. Here's a link for the Cherokee version:
Home Brew Budget Boost
For a Comanche, you use a set of S-10 or Dakota leaves in the rear, and follow the front instructions to the letter.
Here's a recent thread on the subject:
Originally Posted by Natethegreat569
I really wish my truck looked and performed like that one.
'08 BITD Vegas-to-Reno 500 - DNF - Crapped out at about MM 260 - holed oil pan - alternator failure(quit charging, then bearing fail/locked rotor) -
'09 BITB Parker 425 - DNF - Died at MM 126 - Holed oil pan(twice) - broken shock mount(as in off the truck) - ignition failure (water intrusion). (This one really chapped, due to race rules, if we went about 4 miles further, we would have placed 2nd in class,... as it was, DNF)