Allison 1000 Trans Tech

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Duramax LBZ Specs

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Duramax LML Specs

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Allison 1000

Allison 1000 Automatic Transmission



A variant of the Allison 1000 transmission has been offered behind the Duramax since its inception in 2001, at which point the transmission's strength, versatility, and performance far exceeded anything the industry had seen. The transmission was available with 5 speeds from 2001 to 2005, while a 6 speed version has been offered from 2006 to present. Duramax powered pickups are rarely seen equipped with a manual transmission, and the 6 speed manual transmission option would be phased out in 2007 thanks to the Allison's popularity and reputation. Save for a few quirks, the Allison 1000 is generally considered a reliable and long lasting transmission.



Allison 1000 Gear Ratios















* 6th gear available in 2006+ model years.


Allison 1000 Specs


Allison 1000

Production Plant:

White Marsh, Maryland


• Light/medium duty diesel trucks.
• All Duramax diesel equipped Chevrolet/GMC trucks.

Production Years:

• First produced in 1999.
• Produced for Duramax applications 2001 - present.


• 5 speed, 2001 to 2005 model years.
• 6 speed, 2006 to present model years.


Approximately 330 lbs (w/ PTO option).

Max Input RPM:

5,000 rpm.


Dexron-III ATF.





Allison 1000 Features

• External filter eliminates need to change internal filter until overhaul is performed.
• PTO optoinal in 3500 GMC/Chevrolet trucks.
• 2 overdrive gears for better fuel economy. At 60 mph, the 6-speed Allison equipped truck cruises at 1,550 RPM (compared to the 5-speed versions 1,800 RPM engine speed at 60 mph)
• Adaptive learning technology links transmission to engine TCM. Users driver input to calculate & create ideal shift strategies.
• Limp mode locks transmission in 3rd gear if rapid or excessive slip is detected, allowing vehicle to safely brought to service station as soon as possible.
• Tow/Haul mode for enhanced trailer braking control.
• Cold operation mode that allows the engine to rev higher until the engine & transmission have reached ideal operating temperature.
• Torque converter locks for gears 3 - 6. Gears 1 & 2 operate in both locked & unlocked torque converter modes.
• Nominal Max Input Torque capacties: 520 lb-ft (2001 to 2005 model years), 565 lb-ft (2005 model years), 650 lb-ft (2006 to 2007 model years), 660 lb-ft (2008 to 2009 model years), 750+ lb-ft (2010 to present model years).


• Component strength; components robust size allows transmission to manage large quantities of torque.
• Dual overdrive ratios allow for decreased operating RPM & increased fuel economy.


• Insufficient C3 clutch lubrication. The C3 clutch is only lubricated when it is engaged. Can lead to premature failure of this particular clutch.
• C1 & C2 clutch pistons engage clutches from the side (off-center), causing uneven pressure & wear.