I have a 3500 SRW Dodge Ram Crew Cab... I did the same as another poster on here and added a set of Loadrite 5000 to dampen the ride. Truck sits level when I add 25-30 psi in bags. I pulled once w/o the bags and decided it would be a bit better with the bags. I was right. Now 3400 miles into a cross country 3 mo trip and am extremely pleased with the ride.
Bags were fairly inexpensive (no air pump, I inflate them manually with my pancake compressor). If for somereason one should fail I can dump the other side and still tow fairly comfotably with the truck till I repair the leak.
best $250 I spent!