Hmmm... Leaf spring rear....Could be the springs are wrapping up at launch, the car hooks good, then when you get out aways the springs unwrap and the rear of the car lifts, which will unhook the rear end.... Only way I've ever got leafs to work worth a poop is with a set of housing floaters and 30"-32" ladder bars.... and that was with a mono leaf....Are yours multi or mono leaf, and what bushings do you have in them??? I think Moroso used to see some Del-alum bushings for Nova's and Camaro's, they worked ok IF you added a grease zerk to the spring eyes to keep them from binding....