I called city spring 4 years ago to ask for air bags and they suggested Timbren rubber blocks and I've been rockn them ever since no problems at all and I haul 2 quads and trailer off road lots,anyone else using them?
I had them in my 09 dodge 1500. They worked good but did effect the ride. It rode good down the highway, but if you hit frost heaves or bigger bumps you really noticed them. Or if you had just a small amount of weight in the box you really noticed it.