DFC Diesel TH5904507AUSOALBHD Tow/Haul HD Series Auto Speed Of Air Long Block | 2004.5-2007 Dodge RAM 5.9L Cummins

Features:

• Supports up to 900 horsepower output
• Includes heavy-duty Wagler connecting rods
• Balanced rotating assembly for smoother operation
• Comes with Fluidamper for engine harmonics
• Includes HD flexplate for transmission durability
• Built for high-power towing and daily driving
• Machined using Rottler CNC equipment
• Fully remanufactured with all new internals
• Complete long block including cylinder head
• Preset rockers and pushrods for easy install
• 5-year or 160,000 km limited warranty
• Built to exceed OEM performance specs

When You Want Big Power And Street Reliability

If you’re chasing big numbers without giving up daily drivability, the DFC Tow/Haul HD Series Long Block for the 2004.5-2007 5.9L Dodge Cummins is the serious upgrade your truck needs. Designed to handle up to 900 horsepower, this engine delivers raw strength while still being reliable enough for regular towing and street use. Whether you’re hauling a toy hauler across states or stacking work miles every week, it’s built to run hard without falling apart. The balanced rotating assembly keeps things smooth under power, while the Wagler connecting rods give you the confidence to turn up the boost. Add in the Fluidamper and HD flexplate, and you’ve got a long block that stays composed under pressure. It’s not just about brute force, either. This build is engineered to be dependable for the long haul, backed by DFC’s trusted 5-year, 160,000 km warranty.

Strengthened Internals Built To Handle Serious Horsepower

The DFC Diesel Tow/Haul HD Series is built from the ground up to withstand the demands of high horsepower Cummins applications. Every engine begins with a precision-machined block using Rottler CNC equipment to guarantee factory-spec tolerances. It includes a fully remanufactured cylinder head with new valves, guides, and seats, all magnafluxed and resurfaced for lasting reliability. What sets this HD version apart is its heavy-duty internals—Wagler connecting rods, a Fluidamper, an HD flexplate, and a balanced rotating assembly all come standard. These upgrades are key to managing increased power, torque, and engine harmonics when pushing beyond 800 horsepower. This long block retains all the features found in the Street and Tow/Haul Series, making it a well-rounded solution for both work and performance. Ideal for trucks pulling heavy loads at high horsepower, it offers the balance of race-ready parts and real-world dependability.

Fits: 2004.5, 2005, 2006, 2007 Dodge RAM 5.9L Cummins

Notes:

• Designed for 2004.5-2007 5.9L Dodge Cummins engines
• Rated for up to 900 HP (94-98) and 850 HP (98.5-02)
• Ideal for trucks towing or driving between 650-800 HP
• Includes all features of the Street and Tow/Haul Series
• Wagler connecting rods included for extreme durability
• Fluidamper and HD flexplate help control engine harmonics
• Balanced rotating assembly included for smoother performance
• Built to handle high power while remaining streetable
• Rated horsepower measured at the flywheel
• Machined using Rottler CNC for precision tolerances
• Comes with DFC's 5-year or 160,000 km limited warranty
• Requires proper tuning and setup for peak performance

Street Series vs Tow/Haul vs Tow/Haul HD

• Street Series: Ideal for daily driving, light work, and diesel enthusiasts. Focuses on reliability upgrades over stock, with head stud and sealing improvements.

• Tow/Haul Series: All Street upgrades plus added performance parts for higher load and towing power. Supports builds up to ~700 HP.

• Tow/Haul HD Series: The most robust option. Adds heavy-duty internals like Wagler rods and a balanced rotating assembly for 800+ HP capability.

Standard/Auto vs Standard vs Auto

• Standard/Auto: Compatible with both manual and automatic transmissions. Offers the most flexibility.

• Standard: Built specifically for manual transmission configurations.

• Auto: Built specifically for automatic transmission setups.