SUNCOAST GM Duramax LML Allison Transmission 2011-2016

DIESELR SunCoast Allison Transmission (2011–2016 Duramax LML)

The 2011–2016 Duramax LML relies on the Allison 1000 6-speed automatic—proven, but not without weaknesses when exposed to real towing, hauling, or tuned power levels. SunCoast engineered the Ranger, Guardian, and Category Series to eliminate factory shortcomings and deliver long-term reliability, whether you need a stock replacement or a 950+ HP competition-ready build.

Each transmission is hand-assembled, vacuum-tested, and equipped with upgraded clutch technology, billet torque converters, recalibrated valve bodies, and billet hard parts where needed. From daily drivers to dragstrip builds, SunCoast gives you an Allison transmission tailored for your truck’s use case.

Variants

• Ranger (Stock Replacement)
  Perfect for stock trucks needing a direct replacement. Includes Guardian billet torque converter, upgraded clutch packs/steels, recalibrated valve body, filters, wiring harness, and factory deep pan.
• Guardian Towing (Heavy-Duty Work/Towing)
  Built for reliability under heavy loads. Includes custom billet torque converter (or no-converter option), billet plates, custom clutches, overhaul kit, recalibrated valve body, filters, wiring harness, and deep pan. Ideal for daily commercial or industrial towing.
• Category 1 (500 HP)
  Performance-ready build with SunCoast billet triple-disc converter (converter option), proprietary clutch packs, billet plates, and upgraded pistons. Handles tuned daily drivers and towing builds up to 500 HP.
• Category 2 (600 HP)
  Adds billet input shaft and billet flexplate to strengthen the drivetrain. Designed for high-torque towing, aftermarket turbos, and sled pulling up to 600 HP. Available with or without converter.
• Category 3 (700 HP)
  Competition-ready with billet input shaft, billet flexplate, billet P2 planet, billet C2 clutch hub, and triple-disc billet converter (converter option). Recommended for 700 HP race trucks and aggressive sled pull builds.
• Category 4 (950 HP+)
  Extreme build featuring billet input, intermediate, and output shafts, billet flexplate, billet C2 hub, billet P2 planet, and triple-disc billet converter (converter option). Proven for maximum reliability in 900+ HP competition environments.