Alright, since I've last posted in this thread.. I still have the issue. All new tires, both leaf springs are new. Motor was replaced due to rod bearings. I swapped the t-case because my overdrive housing snapped off at the rear and ruined the splines.
I have ever so slight play up and down in my pinion. I know it needs to be fixed, but i'm not convinced thats my issue.
I noticed today for sure that it does it when it wants to, really. If i'm cruising down the highway at about 65 and I let off the gas completely, sometimes it bounced in the rear. If i give it gas it stops.
If I am in stop and go traffic, and i let off the brake and let it roll (maybe 10-15 mph) it bounces. Is it a torque converter issue??
Also, it only does it once it's started. If it decides it's not going to do it during a drive, then it never happens. But once it does it on the highway, it never stops. That's what really boggles me. Still haven't gotten shocks yet.