[joyridin']

On an Arntz, there is a plate on the upper crossmember where the differential mounts. There are outer plates on the upper crossmember where the shocks mount. You can either run the factory style trailing arms to the front, or make your own off the lower outer fulcrum to the rear. The inner fulcrum shaft should go through the frame crossmember.

If you have to fabricate everything yourself, you might want to look at a Corvette rearend from a C4. They are all LSD and parts are a lot easier to find. Maybe even a 8.8 IRS, although they seem to be pretty complicated.