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ATS Built Extreme Allison LCT1000 6-Speed Transmission

2006-2010 GM 6.6L Duramax
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The ATS Built Extreme Allison LCT1000 6-Speed Transmission is the ultimate choice for the 2006-2010 GM 6.6L Duramax owner who wants the most out of their truck. Innovation and technology set ATS apart from the rest. Between the engineering team, and their transmission specialists, ATS has logged thousands of hours in building, testing, and manufacturing to bring you the best Allison Transmission for your truck. The Extreme Transmission includes proprietary modifications to the drums and pistons. ATS has found these modifications are necessary for power over 700RWHP. The pump is also modified more extensively for increased line pressure.

ATS manufactures every clutch used in their transmissions and torque converters. Using their 3-axis high-intensity CNC laser to cut out their clutch steels, ATS is one of the only manufacturers in the industry with these capabilities. This not only ensures the highest quality, but it also gives ATS the ability to modify and improve over the factory components, without having to just buy whatever clutches are already available on the market. ATS Clutch Designs provide the ability to add over 200% torque capacity to the transmission allowing for more power, and heavier loads without compromising reliability. In addition, ATS has formulated their own unique clutch material that is ONLY used in ATS transmissions. It also uses a bonding agent that will not disintegrate with heat or water, once it has bonded with the steel, they essentially become one piece. All clutch material is also bonded in house, which means unparalleled quality control over the parts that YOU rely on to get you to work, down the race track, or through a family vacation.  

Valve Body
The valve body is essentially the brain of your transmission, it’s what routes the fluid to the clutch pack based on which gear it needs to be in. Naturally, this important component was also in need of improvement. A stock transmission will run with line pressures around 90psi. While this is no problem for stock power, it has little room for added torque. With the ATS Shift Kit and the Pump Upgrade Kit, ATS increases pressure up to 250psi. This gives you higher clamping force and provides added torque capacity.  

Add in the optional ATS Co-Pilot and you can reach up to 300psi. Not only does this allow the transmission to hold more power, it allows for quick, crisp shifts with little to no delay in shift timing. So not only do you get through the gears quicker, you will not lose boost or RPM. 

  • ATS Built Extreme Allison Transmission
  • Modified Transmission Pump 
  • Modified A&B Trim Valves 
  • New Gaskets & Seals 
Note: Transmission ONLY. Deep Pan, Torque Converter and CoPilot must be added (sold separately).  

Warranty Information: 
This ATS Automatic Transmission carries a ONE YEAR/ONE HUNDRED THOUSAND MILE (1 yr/100,000 mile) Warranty. This Warranty shall not apply to any automatic transmission that has been improperly stored or installed This Warranty shall not apply to misapplication, improper operating conditions, accidents, or neglect. This Warranty shall not apply to an automatic transmission that has been improperly repaired, maintained and/or altered by the owner or his agent/tech. Most importantly, all transmission shafts are not covered by this Warranty on any transmission due to the capability of certain situations to cause stress-loads beyond the structural ability of the shaft. ATS’ Automatic Transmission Warranty is NOT transferable. It is mandatory for implementation of this warranty that line pressures are tested at time of install. ATS will not pay for any fluids replaced in the event of a transmission failure.

Vehicle Applications

2006 Chevy 6.6L LLY/LBZ Duramax
2007 Chevy 6.6L LLY/LBZ Duramax
2007.5 Chevy 6.6L LMM Duramax
2008 Chevy 6.6L LMM Duramax
2009 Chevy 6.6L LMM Duramax
2010 Chevy 6.6L LMM Duramax
2006 GMC 6.6L LLY/LBZ Duramax
2007 GMC 6.6L LLY/LBZ Duramax
2007.5 GMC 6.6L LMM Duramax
2008 GMC 6.6L LMM Duramax
2009 GMC 6.6L LMM Duramax
2010 GMC 6.6L LMM Duramax


  • Manufacturer Name ATS Diesel
  • Shipping Weight 500.00 lb.
  • Fuel Type Diesel
  • Warranty Yes
  • Warranty Info 1 Year / 100,000 Miles
    View Warranty Form
  • Prop 65 Prop 65 WarningWARNING: Cancer & Reproductive Harm -
  • Internal LR


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Questions and Answers

Will this work with an 2004.5 LLY?
View Staff Answer 

No, the transmission will only fir the 06-07 Transmission LLY/LBZ Engine (Trucks built from Aug-05 to Jul-07) and 07.5-10 Transmission LMM Engine (Trucks built from Aug-07 to Jul-09).

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