Allison 1000 Transmission

Specifications

The Allison 1000 transmission is a heavy-duty, fully automatic transmission widely used in pickup trucks and commercial vehicles, most notably paired with the GM Duramax diesel engine. It is engineered to handle high torque loads, making it especially well-suited for towing, hauling, and demanding work conditions. The transmission uses advanced electronic controls and adaptive shift logic that adjust shift timing and firmness based on driving style, load, and road conditions, which improves performance, efficiency, and driving comfort. Features such as a dedicated tow/haul mode enhance braking control and reduce gear hunting when pulling heavy loads. 

Built with strong internal components, effective cooling, and a reputation for long service life, the Allison 1000 is valued for its durability, smooth operation, and reliability in both commercial and recreational applications.    

Transmission Variants

5-Speed Allison 1000 (2001–2005)

Used with the LB7 and early LLY Duramax engines, the original 5-speed Allison 1000 marked a major step forward in durability for diesel pickups. Early models (2001–2003) were known for occasional harsh or abrupt shifting, which was largely resolved through updated transmission control module (TCM) programming. In 2004, Allison introduced a revised solenoid design that significantly reduced pump noise and improved overall shift smoothness. Despite early quirks, this version earned a reputation for strength and reliability under towing and work conditions.

6-Speed Allison 1000 (2006–2010)

Introduced in the 2006 model year with the LBZ Duramax and continuing through the LMM, the 6-speed Allison 1000 added a double-overdrive sixth gear to improve highway fuel economy and reduce engine RPM at cruising speeds. This generation also introduced a manual select mode, giving drivers more control over gear selection when towing or descending grades. With refined shift logic and proven internals, this version balanced performance, efficiency, and durability, making it a favorite among both daily drivers and heavy haulers.

Updated 6-Speed Allison 1000 (2011–2016)

Paired with the LML Duramax, the updated 6-speed Allison 1000 featured stronger internal components and upgraded electronic controls to manage significantly higher torque outputs. Improvements included reinforced clutches, enhanced cooling capability, and more advanced TCM programming for smoother, more precise shifting under load. These updates allowed the transmission to maintain Allison’s reputation for reliability while meeting modern performance and emissions demands, especially in high-horsepower towing and commercial applications.

Frequently Asked Questions