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Randy's Transmissions  |  SKU: WEBKIT.P20

Randy’s 2001-2019 GM Duramax Allison 1000 Stage 4 Performance Transmission

USD 11,89500

Can I pick up my order or have it installed at your shop?

Absolutely. We offer local pickup on most products and full professional installation at our shop in Washington, MO. Whether you just want to grab your parts or have our techs handle the install, we’ve got you covered. Give us a quick call at 636-429-7020 or message us to schedule a visit — we’ll make sure the parts are ready when you arrive.

How do I know if this part fits my vehicle?

Unsure if it’ll fit? No problem — that’s what we’re here for. Send us your vehicle’s year, make, and model, and we’ll verify fitment before you order. We can also point you toward compatible upgrades or supporting parts if needed.

What if I need to return a product or it’s defective?

Most unused items can be returned within 30 days in their original packaging. Some products are covered by a manufacturer’s warranty as well. If something arrives damaged or doesn’t meet your expectations, just let us know — we’ll help you get it replaced, refunded, or repaired. (Tracking updates are also emailed automatically once your order ships.)

What's the lead time on custom or fabricated parts?

Many of our parts are built to order — especially fabricated or performance components. These can take additional time to produce before shipping. Lead times vary by manufacturer and demand, but we’ll always keep you updated along the way. If you’re working on a tight schedule, reach out before ordering at 636-429-7020 and we’ll confirm current availability or estimated ship dates.

Description

Built for serious power, the 2001-2019 GM Duramax Allison 1000 Transmission Stage 4 Performance Transmission from Randy’s is designed for street and track enthusiasts demanding maximum power transfer and extreme durability. Rated for 900+ horsepower, this Allison transmission features upgraded internal components, increased clutch capacity, and billet-strength components to handle high-performance Duramax applications. MPN: WEBKIT.P20.

Why Choose the Randy’s Stage 4 Allison 1000 Transmission?

  • 900+ Horsepower Capability – Engineered for high-horsepower street trucks, track builds, and extreme Duramax applications.
  • Upgraded Clutch Capacity – Raybestos or ALTO G3 C-3/C-4 Torque Kit with custom machined pressure plates provides increased holding power.
  • Billet Internal Components – Billet input shaft, C-2 hub, output shaft, and P-2 planet provide increased strength under extreme torque loads.
  • Improved Shift Performance – LML-style pistons, return springs, Transgo trim valves, and Ratio Tek pressure upgrades optimize shift quality and fluid control.
  • Heavy-Duty Torque Converter – Randy’s Torque Converter features a billet stator with custom stall options available for performance tuning.
  • Enhanced Cooling Capacity – HD cast aluminum deep pan increases fluid capacity and helps maintain transmission temperatures under demanding conditions.
  • Built for Street & Track Use – Designed for enthusiasts who require reliable performance in extreme conditions.
Kit Includes
  • Stage 4 Allison 1000 Performance Transmission
  • Raybestos or ALTO G3 C-3/C-4 Torque Kit
  • Custom machined pressure plates
  • LML-style pistons and return springs
  • Raybestos or ALTO G3 C-1/C-2 Torque Kit
  • Ratio Tek Pressure Upgrades
  • Transgo Trim Valves
  • New Torrington Bearings
  • Randy’s Torque Converter with Billet Stator
  • Billet Input Shaft
  • Billet C-2 Hub
  • Billet Output Shaft
  • Billet P-2 Planet
  • HD Cast Aluminum Deep Pan
  • New OE Filters
Installation Highlights

The Randy’s Stage 4 Allison 1000 Transmission is built as a performance replacement transmission for Duramax applications. Professional installation is recommended for proper setup, calibration, and long-term reliability.

Fits These Models
  • 2001-2004 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax LB7
  • 2004.5-2005 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax LLY
  • 2006-2007 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax LBZ
  • 2007.5-2010 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax LMM
  • 2011-2015 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax LML
  • 2015.5-2016 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax LML
  • 2017-2019 Chevrolet Silverado 2500HD/3500HD 6.6L Duramax L5P
  • GMC Sierra 2500HD/3500HD Duramax Applications
Specifications
  • Transmission: Allison 1000
  • Power Rating: 900+ horsepower
  • Application: Street and track performance
  • Torque Converter: Randy’s Torque Converter with Billet Stator
  • Pan: HD Cast Aluminum Deep Pan
Key Features at a Glance
  • Stage 4 Performance Build - Designed for high-horsepower Duramax trucks.
  • Billet Strength Components - Handles increased torque loads from powerful diesel builds.
  • Enhanced Clutch Capacity - Provides reliable power transfer under demanding conditions.
  • Improved Cooling - Deep aluminum pan helps maintain transmission performance.
  • Street & Track Ready - Built for enthusiasts pushing their Duramax to the limit.
Notes
  • MPN: WEBKIT.P20
  • SKU: WEBKIT.P20
  • Custom torque converter stall options available.
  • Designed for performance applications requiring increased transmission strength.

SKU: WEBKIT.P20

Questions? We’re Here to Help.

Have questions about upgrades for your Duramax? Contact FASS Motorsports and we’ll get you dialed:

Phone: 636-429-7020

Email: info@fassmotorsports.com

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