DFC Diesel SS6604505LLYSOALB Street Series Speed Of Air Long Block (Standard/Auto) | 2004.5-2005 GM/Chevrolet 2500HD/3500HD 6.6L Duramax LLY

Features:

• 5-year, 160,000 km warranty coverage
• Built for work trucks and daily drivers
• Upgraded for known LLY failure points
• Includes ARP or OptiTorque head studs
• All-new pistons, rings, bearings, and gaskets
• Remanufactured to meet or exceed OEM specs
• Machined using advanced Rottler equipment
• Improved sealing in common leak areas
• Includes gapless Total Seal piston rings
• Woodruff keyed camshaft for added durability
• EDM doweled oil pump gear for longevity
• Pre-set rockers and pushrods to factory spec

Take Your Duramax From Factory Flaws To Street Ready Strength

If you're dealing with a tired or failing LLY engine in your 2004.5-2005 Chevy or GMC 2500HD or 3500HD, the DFC Diesel Street Series Long Block is the solution that brings both reliability and real-world performance back under the hood. Built for everyday work, towing, and weekend driving, this engine doesn’t just match OEM standards, it improves on them. The team at DFC knows the common failure points in these 6.6L Duramax engines, so they’ve addressed them head-on with premium components and carefully thought-out upgrades. With all-new pistons, rings, bearings, gaskets, valves, and more, this long block eliminates the guesswork and gives you peace of mind for the long haul. It also comes loaded with high-quality hardware like ARP or OptiTorque head studs, which are a must-have for added head sealing strength under higher loads. What's more, DFC backs this engine with one of the best warranties in the industry, 5 years or 160,000 km, so you can drive, haul, or tow with full confidence. Whether you're building a solid daily driver or bringing your work truck back to life, this is the kind of upgrade that makes every mile feel like a fresh start.

Built With Precision To Outlast And Outperform Stock

Behind the performance of the DFC SS6604505LLYSOALB Long Block is a meticulous remanufacturing process designed to exceed factory standards in every category. Each engine is machined using advanced Rottler equipment to ensure exact tolerances, then assembled with top-tier parts that meet or surpass OEM quality. The cylinder heads are fully remanufactured with new valve guides, seats, valves, and stem seals, and they’re resurfaced and magnafluxed to catch hidden flaws before they become failures. Inside the engine, Total Seal gapless piston rings are used to improve cylinder sealing and longevity, while the EDM doweled oil pump gear and woodruff keyed camshaft add strength where it counts. The long block arrives with the rockers and pushrods pre-set to factory spec, making installation easier and more precise. Additionally, sealing upgrades have been made in areas known for oil or coolant leaks, helping to reduce maintenance headaches down the road. This engine includes everything from a complete short block and cylinder head to a top-end gasket kit, making it a true drop-in solution for your Duramax LLY platform.

Fits: 2004.5, 2005 GM/Chevrolet 2500HD/3500HD 6.6L Duramax LLY

Notes:

• Designed specifically for 2004.5-2005 GM/Chevy 2500HD and 3500HD trucks with the 6.6L Duramax LLY engine
• Street Series is ideal for daily driving, light towing, and diesel enthusiasts
• Remanufactured using all new industry-recognized name brand components
• Engine includes long block assembly with head, short block, and gasket kit
• Cylinder heads are resurfaced, magnafluxed, and fully rebuilt with new internals
• Block is bored to next oversize piston for proper fit and performance
• Includes either ARP 2000 or OptiTorque head studs based on availability
• Built to address common Duramax LLY failure points for improved longevity
• Backed by DFC's 5-year / 160,000 km (100,000 mi) limited warranty
• Not a complete crate engine, intake, fuel system, and other externals not included
• Professional installation recommended due to precise engine setup and calibration

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.