what causes BAD wheel hop in reverse

I've had this issue of wheel hopping in reverse after doing a auto to 4spd conversion. I can not back up any incline because the rear hops up and down terribly. Now i did do a gear change in the 3rd member that I did myself for the first time. I had other people who have done gear changes look at my setup and they said it looked good. I have no problems going forward, no whine no grind, just can not backup. Checked all springs, mounts, shackles everything looks good. Everything is the same parts as it was when it was a auto. I had a nephew hang out the pass side door to look under the car and he said the front of the rear is tipping down about an inch when trying to backup. Sounds like alot to me. The tranny is an OD tranny. Could the leaf springs be too weak to handle the torque of a clutch setup as oppossed to an auto that has some slippage. Any help appriciated. Thanks Mark