Randy's Transmission 311241035 Stage 4 Allison 1000 Transmission 900+HP Max | 2001-2019 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Features:

• Supports builds up to 900+ horsepower
• Fits 2001–2019 6.6L Duramax applications
• Includes billet input and output shafts
• Billet C-2 hub and P-2 planet gear
• Raybestos or ALTO G3 clutch kits
• Custom machined pressure plates
• LML-style pistons and return springs
• Randy’s Torque Converter with billet stator
• Includes new OE transmission filters
• HD cast aluminum deep transmission pan
• Transgo trim valves and Ratio Tek upgrades
• New torrington bearings throughout build

Serious Strength for High-Horsepower Duramax Builds

If you're pushing your Duramax north of 900 horsepower, your factory Allison 1000 transmission isn’t going to cut it. The Stage 4 build from Randy’s Transmission is designed to handle that level of power with confidence, making it a top-tier choice for performance-driven Silverado and Sierra owners. Built for 2001 through 2019 models, this transmission upgrade isn't just a stronger version of stock—it’s a fully re-engineered system packed with premium internals to take abuse and keep delivering smooth, consistent shifts. From heavy-duty towing to drag-strip launches, this transmission gives you the strength to handle big torque without hesitation.

Built Right with Battle-Tested Components

Inside the Stage 4 build, you'll find nothing but serious hardware. It comes equipped with Raybestos or ALTO G3 clutch kits in both the C-1/C-2 and C-3/C-4 assemblies, matched with custom-machined pressure plates for optimal clamping force. LML-style pistons and return springs improve durability under extreme loads, while new torrington bearings keep things spinning smooth and steady. The billet input shaft, billet output, C-2 hub, and P-2 planet add an extra layer of reliability where it matters most. You'll also get Randy’s own billet stator torque converter and a cast aluminum deep pan to help keep temperatures in check. This transmission is more than a rebuild—it’s a full upgrade for trucks built to go beyond stock limits. Just keep in mind, a $500 shipping surcharge applies, and flexplates are not included for retail or shop installs.

Fits: 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax