If you tow trailers of any weight or use your 1500 Chevy like a 2500, this is for you. My truck is tow modified, modified transmission and rear end to tow (upgraded Eaton posi block with upgraded Race bearings). I also have a few engine upgrades: a Jet Performance chip, upgraded high-lift rocker arms, an upgraded factory Tornado air intake, and a K&N air filter. The rear was the only missing key for towing, but that solved that problem. This fits in a Z71 with a small block Chevy 350 TBI engine (the best engine they've ever built).