Drivetrain› Automatic Transmissions and Components

Allison

6.6L Automatic Transmission

$12,749.00

SKU: 10L1000

In Stock
In Stock
Ships by Sep 12
Free Shipping over $200
$100 Minimum Order
30 Days Return
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Overview

The Allison 10L1000 is a ten-speed automatic transmission, engineered by GM and rigorously tested by Allison engineers. It was developed for the 2020 and later 2500/3500 heavy-duty series GMC Sierra and Chevy Silverado models equipped with the 6.6L Duramax diesel engine. This transmission features high-strength components and offers first-gear torque converter lock-up to reduce heat buildup under high loads.
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The Allison 10L1000 is a robust ten-speed automatic transmission, jointly designed by GM engineers and validated through extensive Allison testing. This transmission is specifically developed for the 2020 and newer 2500/3500 heavy-duty series GMC Sierra and Chevrolet Silverado trucks, featuring the 6.6L Duramax diesel engine. Constructed with high-strength parts, the 10L1000 is built to withstand demanding conditions. Its design incorporates first-gear torque converter lock-up capability, which effectively reduces high heat buildup during heavy loads and towing. The transmission boasts a wide gear ratio spread, ranging from 4.54 in first gear to a .63 ratio in tenth gear, with a reverse ratio of 4.54. The transmission utilizes a comprehensive clutch system, including GPZ friction clutch packs and steel clutch packs. Components include multiple A, B, C, D, E, and F clutch sets, with specific counts for each type, ensuring durable engagement and power transfer. It also features a dedicated transmission filter (part number 515292) for optimal fluid cleanliness and performance.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

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Specifications

BrandAllison
Part Number10L1000
CategoryDrivetrain

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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