My 2000 GMC Sierra rides very rough with no payload . It's a bone-jaring ride. My 1989 Chevy pickups rode much more smoothly, load or no load. In fact, I was always amazed at how smooth the unloaded ride was, and how little rear end sag occurred even with 1200 lb. of payload in the bed. By 2000, GM seems to have forgotten how to make a truck ride well . My GMC has 119,000 miles on it, and may have replacement shocks that make it ride worse than stock. I may also have an optional heavy duty suspension . I'm running 30 lb. of tire pressure in the 16 inch tires , which is a bit lower pressure than recommended. How can I tell if my truck has a heavy duty suspension, or the standard suspension? I bought the truck used, and have no original paperwork.
