My 1998 Chevy C3500 had been lowered by the previous owner. He cooked the front coil springs and removed the rear overloads. He also put dropped shackles in it. No way that was going to haul my 5th wheel that way. The truck was already banging on the axle. First thing I did was put some Firestone air bags in the back. I've since rebuilt the front end, new springs, etc. I haven't done anything to the back except the bags! I keep them at 30 lbs and when it's time to go camping, I raise that to 60-70 lbs. I love them bags!!