General Motors Allison 10L1000 Transmission

Allison 10 Speed Automatic Transmission Specs & Ratios

The Allison 10L1000, or more appropriately GM-Allison 10L1000, 10 speed automatic transmission was introduced for the 2020 GMC Sierra/Chevrolet Silverado HD equipped with the 6.6L Duramax L5P turbodiesel. The transmission is not related to the co-developed GM 10L80/Ford 10R80 10 speed automatic transmission that is found in GMC Sierra/Chevrolet Silverado 1500 and Ford F-150 pickup models.

The 10L1000 was designed by GM engineers whom relied on close collaboration with Allison Transmission throughout the design process, noting specifically that the transmission was "validated" by Allison through rigorous testing and review of GM's design. As the transmission carries the Allison namesake, one can only assume that the 10L1000 has earned Allison's stamp of approval. GM asserts the 10L1000 is entirely separate in design from the smaller 10L80 built for 1/2 ton applications; the gear ratio spread is clearly different between the two transmissions.

GM promises that the 10L1000 will allow the engine to deliver full torque in first gear (a 4.54 to 1 reduction), owing to high strength components and the ability to lock the torque converter in first gear. Doing so reduces the rapid heat buildup common when high loads are transmitted through an unlocked torque converter. Locking the torque converter forces the stator and impeller to spin at the same speed, thus eliminating this source of heat generation and reducing the stresses passed through the converter.

A unique feature of the 10L1000 is its engine powered PTO, which relies on a chain driven assembly within the transmission; its connection to direct engine power allows it to be operated at idle with the vehicle in park. The PTO is rated for a maximum 43 horsepower apparatus at up to a 3,100 RPM maximum speed.

Allison 10L1000 10 Speed Automatic Transmission Ratios












4.54 : 1

2.86 : 1

2.06 : 1

1.72 : 1

1.48 : 1

1.26 : 1

1.00 : 1

0.85 : 1

0.68 : 1

0.63 : 1

4.54 : 1

Allison 10L1000 10 Speed Automatic Transmission Specs


General Motors Allison 10L1000


10 speed automatic

Production Plant:

Toledo Transmission plant Toledo, Ohio

Model Years/Applications:

2020 - current Chevrolet Silverado 2500 HD, 3500 HD pickups
2020 - current GMC Sierra 2500 HD, 3500 HD pickups
2020 - current Chevrolet Silverado 3500 HD chassis cabs
2020 - current GMC Sierra 3500 HD chassis cabs

Case Material:

Cast aluminum



Transmission Fluid Spec (ATF):

GM DEXRON ULV automatic transmission fluid

Service Intervals:

Replace transmission fluid and filter every 45,000 miles

Power Take-off (PTO) Provisions:

SAE "A" style two hole pump mount, passenger side of transmission
SAE 11 tooth internally splined shaft on transmission (transmission accepts external splined PTO apparatus)

Max PTO Power:

43 HP max, 13 GPM max

PTO Speed Range:

700 - 3,100 rpm


• Chain drive engine driven PTO
• 10 forward gears with 3 overdrive gear ratios
• Torque converter lockup available in all forward gears, including 1st