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Wehrli Custom Fabrication 2004.5-2005 LLY Duramax 750+HP Built Transmission - LLY750+HP

  • Must Be Installed by an Authorized Dealer
Please Call for Availability


2004.5-2005 LLY 750+ HP Trans Build Includes standard 750 build with addition of; Billet Input and Output Shafts, P2 Billet Planet Fix with P1 Mod, Billet C2 Clutch Hub, C3 Oiler PTO Covers, and Goerend Deep Pan.

All WCFab Built Allison Transmissions are assembled in-house in our climate controlled clean room. With over 10 years of combined experience and hundreds of builds in use to date, we have been able to tweak and perfect our builds to get the most out of the Allison to withstand the power that we are able to produce with the Duramax. We offer three build levels: 550HP, 750HP, and 750+HP.

All our builds start with a COMPLETE disassembly of the transmission for inspection of all components. All parts are washed in our ultrasonic parts washer to ensure a clean, contaminant-free rebuild. When reassembly starts we use a Raybestos Clutch Kit (in 750hp and 750+ builds) custom tailored to our specifications. 2001-2010 model year units are upgraded to OEM LML style C3/C4 clutch apply pistons and return assemblies to allow for faster disengagement of these clutches which allows for quicker, smoother shifts. RatioTek and Trans-Go Shift Kit in the valve body and stator to increase clutch holding power, and to ensure reliability at the higher pressures the fluid pump is freshened on 6-speed applications and on 5 speeds the pump is replaced with an upgraded 6-speed style unit. For additional strength on all builds we install a billet sleeve on the factory C2 hub to prevent disengagement and stripped splines. On every build the following items are replaced with genuine new Allison parts; Torrington bearings, NSBU/ internal mode switch, pressure manifold switch, valve body wire harness seals, valve body solenoids, gaskets, internal filter with billet lock and a genuine Allison external filter with a new magnet. Replacing the above components offers you peace of mind and a complete, freshly overhauled transmission, it’s LIKE NEW! Failed electrical components can leave your truck dead on the side of the road, we want 100% Satisfaction with your transmission not just today, but in the years to come. We only use genuine OEM Allison Components throughout the rebuild and no corners are cut on our built transmissions. Our build is finally completed with a semi-gloss black professional paint job (Powder coating is available at an additional cost), powder coated PTO covers and rounded off with an Allison deep transmission pan and zinc plated external hardware package.

Which build is right for you?

1. The 550HP build gives you a level of confidence for your daily driver, farm, work, or toy hauling truck. A great replacement for your high mileage, worn out factory transmission, this performance package utilizes all the components mentioned above with OEM shafts and a triple disk performance torque converter. This transmission is best suited for use on tune only applications with the OEM turbo and fuel system. It is not meant for boosted launches, drag racing, truck pulling, or modified applications over 550 rear wheel horsepower.

2. The 750HP build is your next step performance rebuild geared towards trucks used more often in racing and competition applications with an upgraded turbo charger(s) and fuel systems. Meant for a maximum of 750 rear wheel horsepower this build utilizes all the components mentioned above with high-performance clutches, OEM shafts, and a triple disc billet performance torque converter.

3. Our third option, the 750+HP is for the all-out racer with a fully built engine and capabilities to exceed over 750HP. This build utilizes all of the components as our standard 750HP build, with the addition of a billet P2 planetary modification, billet input and output shafts, billet C2 hub, modified P1 Sun gear, Goerend Deep Transmission Pan, and topped off with a set of C3 oiler PTO covers (for 2001-2016 models) which are also an option on our 750HP Build as we drill all main cases to accept the benefits of C3 oiler covers just in case you choose to add these covers later.

Torque Converters are spec’d out based on each individual trucks turbo setup, horsepower goals, or usage. Please call the shop or email us if you need help choosing which converter is best for your application.

**Torque Converter and Our Labor and Workmanship is Covered under a 3 Year Warranty from Invoice Date (550HP build carries a 1 year warranty on converter). We do offer an extended warranty increasing the warranty to a total of 5 years for an additional $495.00**

**Not included in price - Labor on installation, Fluids, Core Fee, or Freight.**

**Must Be Installed by an Authorized Dealer**

**Transmission Cooler and Lines MUST be Flushed prior to install or Warranty is VOID**

Product Notes

-Not included in price- Labor on installation, Fluids, Core Fee, or Freight.
-Must Be Installed by a Qualified Mechanic
-Transmission Cooler and Lines MUST be Flushed prior to install or Warranty is VOID



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