One of the biggest downfalls of your 2004.5-2005 GM 6.6L Duramax is the lack of fluid capacity in your transmission pan, leaving a lot to be desired when it comes to proper heat dissipation and functionality of your transmission. Our selection of transmission pans are precision-engineered to increase fluid capacity and cooling fins to provide enhanced cooling efficiency. The upgraded fluid capacity that delivers impressive heat dissipation even when towing or hauling heavy loads. In addition, we offer premium filters and transmission fluid to ensure long-term reliability. Check out our selection of Transmission Coolers & Lines for additional cooling capability! GM Duramax Fitments: 2004, 2005 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.