DFC Diesel TH5998599SOALBHD Tow/Haul HD Series Speed of Air Long Block (STD/Auto) | 1998.5-1999 Dodge Ram 5.9L Cummins 24V

Features:

• Fits 1998.5–1999 Dodge Ram 5.9L 24V Cummins
• Rated for up to 850 horsepower output
• Includes all Street and Tow/Haul upgrades
• Wagler connecting rods for extreme durability
• Fluidamper included for improved harmonic control
• Heavy-duty flexplate supports high torque loads
• Fully balanced rotating assembly for smooth power
• Built for street use and heavy towing
• Speed of Air Hyperformance piston technology
• Backed by 5-year, 100,000-mile warranty
• Designed for severe-duty performance applications
• Perfect for high-load, high-power Cummins builds

Built for Heavy Towing, Daily Driving, and Big Power

When your truck pulls double duty—towing heavy trailers during the week and laying down serious horsepower on the weekends—you need an engine that can handle both without compromise. The DFC Diesel Tow/Haul HD Series Long Block is built exactly for that balance. Designed for the 1998.5–1999 Dodge Ram 5.9L Cummins 24V with standard or automatic transmissions, this engine is the most capable version of DFC’s lineup. It takes everything from the Street and standard Tow/Haul Series and builds on it with serious internal upgrades. That means you still get Speed of Air™ Hyperformance pistons for cleaner combustion, faster turbo spool, and noticeable gains in drivability, throttle response, and fuel efficiency. But the HD Series raises the bar even higher—engineered to comfortably support street-driven builds pushing 650 to 800 HP, with the structural integrity to handle up to 850 HP at the flywheel.

Strength Where It Matters, Backed by Proven Engineering

Inside the Tow/Haul HD, you’ll find Wagler connecting rods, a Fluidamper for improved harmonic balance, and a heavy-duty flexplate, all connected to a fully balanced rotating assembly that ensures the entire bottom end can handle high stress without flinching. These aren’t flashy bolt-ons—they’re critical reinforcements that keep the engine alive under big boost and brutal towing conditions. Whether you’re pulling heavy up mountain grades or chasing big numbers with aftermarket tuning, this engine holds its ground. It’s not just about brute strength either—precision machining ensures every component fits tighter than factory tolerances for longer life and better oil control. Backed by a 5-year, 100,000-mile warranty and built to meet the demands of severe-duty applications, this long block is ideal for Cummins owners who want maximum performance without sacrificing reliability. If you’re serious about your truck’s capability and want peace of mind behind the wheel, the HD Series delivers.

Fits: 1998.5, 1999 Dodge Ram 5.9L Cummins 24V

Product Image Note: Some images may be representative.