ATS 309-814-4290 Stage 1 Allison LCT1000 Crate Transmission | 2004.5-2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY 4WD

Features:

• Includes Stage 1 performance transmission
• Built for 2004.5–2005 Duramax LLY 4WD trucks
• Comes with Five Star torque converter
• Includes ATS deep transmission pan
• Ideal for light towing and mild performance
• Improves shift quality and durability
• Upgraded internals for better torque handling
• Reduces heat with larger fluid capacity
• Maintains drivability with added performance
• Perfect for daily-driven and work-ready trucks
• Built and tested in the USA by ATS Diesel
• Professional installation is highly recommended

Let Your Truck Shift With Strength And Confidence

If your Duramax LLY is starting to show signs of transmission fatigue, or you’re prepping it for heavier work and towing duty, the ATS Stage 1 Allison LCT1000 Crate Transmission is the upgrade your truck has been waiting for. Designed to bring life back into your 2004.5–2005 Silverado or Sierra, this setup delivers improved strength, cleaner shifts, and the kind of confidence you want when you're hauling serious weight or running a tune. It includes everything you need to replace and enhance your transmission in one shot—ATS's proven Five Star torque converter and a deep pan to manage heat and extend fluid life. Whether you're daily driving, towing your camper, or building out a reliable work rig, this package keeps your truck ready for whatever the road or trail throws at it. It’s not about making your truck something it’s not—it’s about letting it perform like it should. This is a smart move for anyone who wants reliability with just the right touch of performance. Your truck does the heavy lifting—this helps it do it better.

Engineered To Support Towing Tuning And Longevity

The ATS 309-814-4290 Stage 1 Transmission package is purpose-built for 2004.5–2005 GM 2500HD and 3500HD trucks equipped with the 6.6L Duramax LLY engine and a four-wheel-drive configuration. At the heart of this package is the performance-enhanced Allison LCT1000 transmission, featuring upgraded clutch packs and improved shift strategies to handle added torque from towing or light engine tuning. Included is ATS's Five Star torque converter, which increases torque multiplication while reducing slippage under load, offering smoother power delivery and improved throttle response. To keep everything cool, the deep transmission pan expands fluid capacity and improves thermal control during extended use. This system is ideal for trucks that are used for towing, hauling, or daily driving under more demanding conditions than stock components were originally built for. Everything in the kit is built and tested by ATS Diesel in the USA, giving you peace of mind and consistent performance. It is a dependable solution for those who need more from their drivetrain without sacrificing comfort or control.

Fits: 2004, 2005 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LLY 4WD

Notes:

• Designed specifically for 2004.5–2005 GM 2500HD and 3500HD trucks with 6.6L Duramax LLY and 4WD.
• Includes ATS Stage 1 transmission, Five Star torque converter, and deep transmission pan.
• Intended for trucks with stock to mildly tuned engines and moderate towing use.
• Transmission provides firmer shifts and enhanced durability under load.
• Professional installation is strongly recommended for proper operation and warranty coverage.
• Torque converter reduces slippage and improves low-end torque transfer.
• Deep pan increases fluid capacity to help manage high operating temperatures.
• Verify transmission compatibility using VIN and drivetrain details before purchasing.
• Transmission is built and tested in the USA by ATS Diesel.
• A $500 shipping surcharge will be added at checkout and is not included in the listed price.