311241030 Stage 1 Allison 1000 Transmission

Features:

• Fits 2001-2017 6.6L Duramax HD trucks
• Built for up to 500 horsepower
• Includes Raybestos C-3 and C-4 packs
• Extra clutch count for added holding power
• Randy's single disc billet torque converter
• Modified lock-up valve for better control
• Transgo trim valves enhance shift performance
• Comes with new bonded pistons
• Includes new C-1 and C-2 clutches
• All new bearings installed during build
• RatioTek pressure kit included
• Built to order with 3 week turnaround

A Stronger Transmission for Real-World Power

If you're building a 2001 to 2017 Silverado or Sierra HD with the 6.6L Duramax and plan to push it up to 500 horsepower, the Randy’s Transmission Stage 1 Allison 1000 is built with that goal in mind. This is not just a refreshed factory unit, it’s a purpose-built upgrade designed to handle more power and deliver smoother, more confident shifts under load. With Raybestos C-3 and C-4 clutch packs featuring added clutch count, this transmission is ready to handle the kind of torque that would overwhelm a stock setup. Whether you’re towing heavy, running a mild tune, or just need something more dependable than factory, this build steps up to the task.

Performance Where It Matters Backed by Proven Parts

Inside, you'll find new C-1 and C-2 clutches, bonded pistons, and all new bearings to ensure long-term reliability. A RatioTek pressure kit and Transgo trim valves are included to fine-tune pressure and shift quality, giving you better control and responsiveness. The single disc billet torque converter from Randy’s is the centerpiece of the upgrade, offering improved lock-up performance and greater strength under load. Every transmission is built to order with an average three-week lead time, and shipping includes a round-trip freight charge. If you're looking for a transmission that can handle the power without getting in the way of drivability, this Stage 1 build delivers the balance you need.

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