I find that the ride on my half ton is stiff but not bouncy. I went through the suspension and replaced all the spring shackles, bushings, u-bolts, and shocks on all four corners. That made a significant differance. It was originally bouncy, loose, and stiff. Now its just stiff, but it gets much smoother with 500 pounds or so in the bed. I have radial tires, it doesn't wander or vibrate.
I also have a very good condition original seat. I believe that really does improve the butt feel. These trucks have very short front leaf springs and they don't have much suspension travel.
One thing that can happen if you have old springs is that you wear a groove where each leaf rubs against the one above it. Then, as you hit large bumps, the leaves hang up on the grooves and make for funny stiff bounces. The only way to fix this is to get new springs.
