2001-2004 Silverado & Sierra 2500 & 3500 Duramax LB7 Complete Transmissions

The Duramax LB7 under the hood of your 2001-2004 Silverado or Sierra can make a surprising amount of power and still handle heavy towing, even compared to modern trucks. However, the 5-speed Allison transmission behind it is likely tired after two decades on the road. Tier One's built transmissions for 2001-2004 Silverado & Sierra 2500 & 3500 Duramax LB7 trucks are designed to breathe new life into your truck. We replace weak factory components with high-performance clutches, billet shafts, and hydraulic upgrades that allow our transmissions to hold massive horsepower and torque. We have everything from Duramax towing transmissions that can handle heavy hauling to all-out Duramax competition transmissions that can hold over 1000 horsepower. Even the best transmission build needs a reliable connection to the engine, so if you are piecing together your own build or need a specific stall speed, look at our 2001-2004 Duramax LB7 Torque Converters. Protect your investment from heat while towing by adding one of our 2001-2004 Duramax LB7 Transmission Coolers. If you aren't ready for a complete transmission swap but want to fix shifting issues, a valve body replacement is a great place to start, so check out our 2001-2004 Duramax LB7 Valve Bodies. To get the most out of your new transmission, consider upgrading your fluid capacity or installing a thermal bypass valve from our section of 2001-2004 Duramax LB7 Transmission Parts.