I just bought a 91 Dodge D350 Single Wheel 4x4 for a toy and it's rough as Hell!! Any pointers on getting a smoother ride????

 

Change the spring packs out. You probably have 2 thick leafs per side on the front. If you go to a spring pack that has more springs (but thinner) you will get a better ride. Also longer springs tend to ride better and articulate better also. Ther's an article in the latest FopurWheeler or 4 Wheel and Offroad (can't remember which) that goes into detail about springs. Check your shocks too, old worn out shocks don't help matters any.