If the truck sits at the height you like the inexpensive way to do at least some improvement is to take the springs off and take them apart and clean them up and either lube them between the leaves or put some strips between them to help them slide against each other smoother.
It's dark, cold and windy outside so I can't run out and take a few photos but what is normally done is that you take the spring pack apart and after generally cleaning all of the leaves up you do a bit of work on them to help them slide against each other smoother.
That includes rounding off the bottom side of the tip of each leaf where it contacts the leaf below it. Then smoothing out the indents the leaves put in the leaves below them. Part of the rough ride is the leaf above catching in the notch it made in the leaf and not sliding smoothly.
Rather than grease many folks use one of the poly liners for springs like this
https://www.classicparts.com/1947-59...ctinfo/74-935/ between the leaves.
That will probably lead to Replacing the bushings and pins in a "while I am at it" thing.
The older rigs like to be greased often. As in at least every thousand miles. That in it's self helps the ride if you keep the bushings greased.