Adding larger tires to your GM 2500HD/3500HD causes both a loss in both power delivery and acceleration. Gain back your performance and acceleration by adding more aggressive rear-end ring-and-pinion gears to your rig. Shorter gears can also give your GM 2500/3500 back the final drive ratio lost from adding larger tires, delivering the performance needed for every application. Pair your new gear setup with a set of Wheels & Tires! GM Duramax Fitments: 2001, 2002, 2003, 2004 GM 6.6L Duramax.Submodel Fitments: WT, Custom, LT, LTZ, High Country, 1LT, 2LT, Pro, SLE, SLT, AT4, Denali.Some exceptions apply, please see individual product pages for specific fitments.