Tom, "bounces like crazy" sounds like shock absorbers are shot. Gas shocks will give you the best all around performance and ride. First thing you should do is check all the suspension components to make sure there isn't something broken, bent, or loose. Also, check the upper shock mount points on the rear. They're often prone to stress cracking around the mount points. If so, you'll need to repair those areas before replacement. Most of the "classic" chevy outlets sell patch pieces that also act as reinforcement.