What shocks did you run? The TC shocks? I scrapped them pretty quickly and went to Bilstein 5100's. That helped. This Spring, when I put my home built traction bars on, that helped the "frame beaming" over expansion joints alot. Kind of transfers some of the energy away from the rear springs. Putting about 1000lbs of motor in the bed made that thing ride like a caddy coming back from Burkhard's shop over some crappy roads in Michigan.
I was more concerned with you spitting a block out with out the traction bars when pulling, the increased ride quality was a plus. I don't pull, but I wanted the bars to eliminate the axle wrap when pulling out hard. They've cured that too.