I know I have never worried about a motor GM built thats one thing they know how to do better than anyone else (exceptions 307,350 diesel, 6.5's) there little I-6 is a power house in my moms XUV and that is a large truck and it will get up and go. My dealer did just pick up an 07 Classic GMC Reg Cab Short Bed Z71 2LT with a 5.3 and 4.10's. I thik I can snag it for 10K it has about 30K miles on it. BUt it's white