Stage 1 Allison LCT1000 Crate Transmission

Features:

• Fits 2003–early 2004 LB7 Duramax 2WD trucks
• Includes ATS Five Star torque converter
• Deep transmission pan improves cooling
• Built for towing and performance driving
• Increased clutch capacity for better durability
• Ideal for stock or mildly tuned trucks
• Enhanced power transfer and efficiency
• Reduces slippage under heavy load
• Preassembled for easy drop-in installation
• Engineered for daily driving and hauling
• Backed by ATS performance engineering
• $500 freight charge applied at checkout

When Dependability Matters You Want Proven Performance

If your 2003–early 2004 Duramax is starting to feel like it’s struggling under load or slipping through gears, it might be time for a serious upgrade. The ATS Stage 1 Allison LCT1000 Crate Transmission isn’t just a replacement, it’s a performance-focused solution for trucks that work hard and drive harder. Whether you’re hauling a trailer, tuning for more power, or just tired of babying your stock transmission, this package gives you the confidence to push your truck without hesitation. It’s built to handle the demands of daily towing, heavy loads, and long miles without breaking a sweat. The included Five Star torque converter delivers tighter engagement and smoother acceleration, so you get more usable power when you need it most. And with the ATS deep transmission pan, your fluid stays cooler under pressure, especially during summer heat or steep pulls. If you want peace of mind every time you shift into gear, this is the transmission that’s ready to back you up.

Every Component Is Designed With Purpose And Precision

This ATS Stage 1 LCT1000 transmission is specifically engineered for 2WD 2003–early 2004 Silverado and Sierra 2500HD/3500HD trucks with the LB7 Duramax engine. The internals feature upgraded clutch packs and fine-tuned hydraulic circuits to improve shift timing, line pressure, and durability under strain. The Five Star torque converter included in this package isn’t just stronger, it’s been carefully calibrated to enhance power transfer and reduce slippage during heavy throttle or towing. Alongside that, the ATS deep transmission pan increases fluid capacity and improves cooling efficiency, which is essential when you're pulling weight or spending time in high-heat environments. Each transmission is built as a complete drop-in unit, ensuring proper alignment and compatibility with your factory systems. While it's built for daily use, this setup is more than capable of supporting trucks with light performance mods or ECM tuning. From top to bottom, this system is designed to outperform factory specs and deliver consistent reliability for the long haul.

Fits: 2003, 2004 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax 2WD

Notes:

• Compatible only with 2WD 2003–early 2004 LB7 Duramax models
• Not suitable for 4WD or late-2004+ Duramax trucks
• Package includes transmission, torque converter, and deep pan
• Built for trucks with mild tuning and towing demands
• May require professional installation for optimal performance
• Transmission is built to order and may require lead time
• $500 shipping surcharge will be added during checkout
• Core return policy may apply—check with seller before purchase
• Designed for drop-in fitment but verify vehicle compatibility first
• Ideal solution for worn, slipping, or overheating stock transmissions
• Ensure cooling system and driveline components are in good condition