Let me tell you my story,,, I had a 1980's S10, one with a bad transmission at 86K miles. Chevy and the BBB accpeted claims, I went through the ordeal and was a stinking waste of time. I swore never to buy another GM. (I had in the past owned 1961 chevy II convertible, 1976 Vega, 1975 nova, 1968 belair, 1974 nova, 1972 cutlass, 1978 cutlass, 1976 el camino, 1986 6000 (Pontiac), 1980 sunbird, 1973 riviera, 1970 cutlass, 1970 camero, and I'm sure a few I forgot. Well anyways I switched to Ford and Mercedes, since the early 90's. I saw my suburban on craigslist, only 128K miles, second owner, oil changes, fuel, tires, etc documented. so I went back on promise to myself, I couldn't resist this low mileage Diesel. I need a diesel to burn some WVO that I have accumulated. And to tow my tandem axle trailer, the F150 just isn't quite up to pulling. I have a few questions, what does C20 designate? My buddy hase a 3/4 ton P/U and it's got 5 lugs, my C20 has 8 lugs and it's a 3/4 ton too. Do I have a heavy duty suspension upgrade on my truck, or what?