11-16 Duramax Merchant Automotive Allison Maximum Transmissions

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  • Regular price $4,499.00



The 5-speed and 6-speed Allison automatic transmissions backing the Duramax diesel engines in GM 2500HD and 3500 pickups is a smooth-shifting transmission that works very well in stock applications. But the factory Allison transmissions tend to have issues coping with heavy towing and hauling or even mild performance upgrades not to mention serious struggles with high performance modifications. As the go-to Duramax and Allison Specialists the team at Merchant Automotive developed the MAximum Transmission Work Series and Pro Series transmissions to provide a reliable alternative to factory rebuilds or replacements in 2001 to 2016 GM vehicles equipped with an Allison automatic transmission.


The MAximum Transmission Work Series was designed for hard working Duramax owners and daily drivers that want more holding power than stock while maintaining the smooth performance characteristics of a stock Allison transmission. The precisely rebuilt Work Series Allison transmissions start with thoroughly tested and inspected Allison cores that are handled by transmission specialists in house at the Merchant Automotive facility in Zeeland, MI. Carefully selected and matched internal components including improved friction materials, hydraulic upgrades, and a dyno tested MAximum Series valve body are meticulously installed. A steel Allison deep sump transmission pan is used for additional fluid capacity along with a billet aluminum Merchant Automotive filter lock to make sure the filter does not come loose. A single disk billet torque converter is included to transfer the power from the Duramax diesel engine directly into the Allison transmission. Each Work Series MAximum Transmission is painted orange and comes completely assembled and is ready to install with 24 quarts of high quality fully synthetic CAM2 Dexron VI automatic transmission fluid to fill the transmission once it is installed.


For owners who are making more power, expect to make more power in the near future or plan to compete with their trucks the MAximum Pro Series transmission is the optimum choice. The Pro Series builds upon the Work Series foundation with additional enhancements to further increase holding capability and durability. Additional clutch apply area and heavy-duty friction material work together with even higher hydraulic pressure to handle high performance applications that stock transmissions can only dream of. It also includes all new bushings, bearings, and seals along with a high-performance dyno tested MAximum Series valve body. To further enhance the performance of the Pro Series MAximum Transmission the torque converter has been upgraded from the previous high-performance standard triple-disk billet torque converter to the pinnacle in diesel torque converter performance with a FIVE-DISK billet torque converter to channel the power from even highly modified Duramax diesel engines into the transmission without wavering. Like the Work Series, each Pro Series transmission is painted orange and comes completely assembled and is ready to install with 24 quarts of high quality fully synthetic CAM2 Dexron VI automatic transmission fluid to fill the transmission once it is installed. Optional billet input, intermediate and output shafts can be added to the Pro Series transmissions to increase power handling capabilities for high-powered competition use such as sled pulling and drag racing.

"We don't play horsepower rating games with our MAximum Transmissions; we just build high-quality transmissions with high-quality parts that hold up to common abuse!" Exclaims Eric Merchant Automotive Founder. He continues, "We can build a MAximum Transmission to hold up to any performance level a customer needs, I run one in Ol' Blue, our 1,700 horsepower UCC competition truck and we can build one for you too!"


Configurations available for 2001-2016 Duramax Diesel applications.

2500HD 3500 Silverado Sierra 6.6L V8 Duramax diesel engines:



2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016



Broken / Cracked Bell housing


Main Case Damage


Extension Housing Damage


Missing - Torque Converter


C2 Hub / Planetary Damage


Broken Input/Output Shaft


Pump / Stator Damage


Rotating Drum



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