2004.5-2005 GM Duramax 6.6L LLY Transmission Modules

It's an unfortunate fact that your 2004.5-2005 GM 6.6L Duramax LLY's transmission will have trouble calculating the right time and place to change gears after upgrading and modifying your engine, resulting in rough and unreliable transmission shifting. In order to prevent this from happening, pick up any of these premium transmission control modules to send the proper OBD II codes to your Sierra/Silverado's computer for consistent gear shifting in every situation. Aside from it's vital link between your transmission and engine, these modules are designed to alert you if it happens to detect any malfunctions or other carious issues associated with your GM 2500/3500's transmission. This helps prevent serious damage to the trans and potential time-intensive repairs in your future. 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.