TH5998599SOALB Tow/Haul Series Speed of Air Long Block (STD/Auto)

Features:

• Fits 1998.5–1999 Dodge Ram 5.9L 24V Cummins
• Built for towing, hauling, and performance
• Supports power levels up to 700 horsepower
• Includes DFC long block assembly
• Speed of Air Hyperformance piston technology
• Total Seal gapless piston ring set
• Stage 3 performance camshaft installed
• 103lb heavy-duty valve springs included
• Manton HD pushrods for added strength
• ARP or OptiTorque head studs installed
• Cometic MLS performance head gasket set
• Thermal-coated pistons for heat resistance

Built to Handle the Load Without Breaking a Sweat

If your 1998.5–1999 Dodge Ram 5.9L Cummins is tasked with serious towing or heavy hauling, reliability isn’t a luxury—it’s the foundation. The DFC Diesel Tow/Haul Series Speed of Air Long Block was engineered for trucks that work hard and don’t have time for downtime. Based on DFC’s proven Street Series foundation, this long block ups the ante with critical upgrades that turn your Cummins into a true workhorse. Whether you're pulling a heavy trailer through mountain passes or stacking miles with a loaded bed, this engine gives you the confidence to push through without hesitation. It includes DFC’s precision-machined long block assembly, but what really sets it apart is the inclusion of Speed of Air™ Hyperformance piston technology, which uses CNC-machined turbulators and aerospace coatings to deliver cleaner combustion, better fuel efficiency, and faster turbo spool-up. That means more usable torque down low and a smoother, more responsive throttle feel—perfect when you're towing uphill or accelerating with weight behind you.

Towing Muscle, Engineered for Endurance

DFC didn’t stop at smoother operation—they built this engine for true high-load durability. Inside, you’ll find a Stage 3 camshaft, 103lb heavy-duty valve springs, and Manton HD pushrods, all working together to handle higher RPMs and the increased stress that comes with demanding applications. A Cometic MLS head gasket set is paired with ARP Series 2000 or OptiTorque head studs, depending on availability, to keep everything locked down under boost. Ceramic-coated piston crowns help manage heat, while dry-film coated skirts reduce friction, extending lifespan under heavy use. Even the little things, like a bolt-in aluminum rear freeze plug, are included to eliminate common failure points. This engine isn’t just rebuilt—it’s reinforced in all the right places to give you more pulling power, more dependability, and less maintenance. So whether you’re stacking miles on the highway or crawling through job sites, this long block is built to show up, haul hard, and last longer than the truck it’s in.

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

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