Drivetrain› Automatic Transmissions and Components

DuraMax Tuner

LLY (2004.5-2005) 6 SPEED DT550 - BUILT TRANSMISSION WITH TORQUE CONVERTER CORE CHARGE OF $1500 APPLIES

$7,815.00

SKU: D06C DT550-LLY-6SPEED-TQC

In Stock
In Stock
Ships by Jun 20
Free Shipping
Non-Returnable Item
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Description

The DT550 built transmission is designed for 2004.5-2005 Duramax owners who regularly use their trucks, tow heavy loads, or desire a more reliable Allison 1000 transmission. This pre-built Allison transmission features new/upgraded clutches and steels, electronics, sensors, valve body, return springs, and an upgraded Goerend billet torque converter. The 6-speed LLY DT550 version includes the DuramaxTuner 6-speed conversion with custom TCM tuning tailored to your specific truck, providing a double overdrive (14% RPM reduction), less road noise/vibration, and improved fuel economy.

Fitment

Fitment Guaranteed

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Log your build in the MOTORMIA app and we’ll guarantee this part fits your exact setup — or your money back, return shipping covered.

Available on iOS & Android

Specifications

BrandDuraMax Tuner
Part NumberD06C DT550-LLY-6SPEED-TQC

Videos

DURAMAXTUNER.COM - BUILT TRANS

DURAMAXTUNER.COM - BUILT TRANS
I CAN'T BELIEVE THIS DURAMAX 6 SPEED CONVERSION MADE THIS MUCH OF A DIFFERENCE!!

I CAN'T BELIEVE THIS DURAMAX 6 SPEED CONVERSION MADE THIS MUCH OF A DIFFERENCE!!
2005 GMC Sierra 2500HD - Duramax Tuner 6 Speed Conversion

2005 GMC Sierra 2500HD - Duramax Tuner 6 Speed Conversion

Buy with Confidence

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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