Kelderman 4 link... best of the best.
You will always have a compliant ride.... empty or fully loaded..and always be level.... with no hassles.
https://kelderman.com/shop/2011-gm-2500-3500-4-link-rear-air-suspension
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I installed a full kelderman air ride system on a 16 dodge for a customer. This system replaces the factory coil springs. Install ride sensors on all 4 corners and it will do all kinds of cool ****. I had it programmed to lower the truck at hwy speed to improve fuel mileage. The customer also wanted a loading and unloading feature for his dirt bikes. The truck was so tall the ramp was crazy steep trying to unload his bikes. Unload would slam the rear to the bump stops and put the front to max height. End result would lower the tailgate 10" closer to the ground. You could control everything from your phone. Cool stuff. Eric