Welcome-
Quite possibly your truck might have been setup just to haul a lot of weight. That diesel engine used to weigh a lot more than that small block. Without the weight it will ride horrible.
For suspension upgrades for ride quality I'd recommend:
1) Tuff Country softride front springs
2) Remove front sway bar or buy a disconnect kit for it. This will make a big difference in the ride if a lifted truck.
3) Buy some quality shocks. I like Bileteins...
4) Rear suspension... depends on what leaf spring packs you have and if they added add-a-leafs to it to stiffen it up even more. (might have to remove leafs or just get a new set of stock replacement springs). With a standard leaf pack installing a shackle flip can make it ride a lot nicer and still maintain load carrying capability. The stock shackle is pretty much stuck in place. With a shackle flip it is now able to flex and move thus soaking up a lot of the bumps. Shackle flips start at a 2.5" lift.
5) Greasable bushings are nice to allow the springs to flex and move also.
6) Tire pressures and sizes. My truck had 235/85R16s on it once upon a time. Original owner had all 4 at 80 psi. Might as well have solid rubber tires. I changed to 265/75R16 then 285/75R16 tires at about half the pressure and they both rode a lot better.
7) Or for the best ride look at Alcan or Deaver springs. $$$ but very nice.
http://offroaddesign.com/catalog.htm
This is a good place to check out and learn about suspension and what upgrades are available.