Chevy LLY Duramax Cylinder Head Set

Upgrade your 6.6L LLY Duramax with a fully remanufactured, precision-engineered complete set (pair) of cylinder heads from Choate Engineering Performance. Built from pressure-tested OEM cores and re-engineered to fix factory failure points, this set delivers unmatched sealing, valvetrain stability, and long-term reliability for your 2004.5–2005 GM Super Duty. Choose Your Model Tier Select the tier that matches your truck’s setup, workload, and performance goals from the dropdown options above: Features & Specs Daily Driver Set Stock to Light Duty Workhorse Set Heavy Towing & Tunes Workhorse Plus Set Extreme HP & Max Boost Best For Daily driving, stock replacements, and light towing. Heavy-duty work trucks, frequent towing, and moderate performance tunes. Heavy sled pulling, drag racing, high-horsepower tunes, and extreme towing builds. Custom O-Ringed Decks — Included Included Valve Springs & Retainers New/Upgraded New/Upgraded Upgraded Heavy-Duty (HD) Springs Lifter Longevity Fix Included Included Included Airflow & Component Upgrades Included Included Included Vehicle Compatibility This cylinder head set fits the following engine applications: 2004.5–2005 GM 6.6L LLY Duramax Turbo Diesel — Fits Chevrolet Silverado 2500HD/3500 & GMC Sierra 2500HD/3500 platforms. The Choate Advantage (Standard on All Sets) Every pair of Choate LLY Duramax cylinder heads undergoes an aggressive remanufacturing and blueprinting process designed to solve original factory design flaws: Hydraulic Lifter Longevity Fix: We alter the valvetrain blueprint and valve stem heights to completely remove excess preload on the hydraulic lifters, drastically reducing wear and extending lifter life. Brand-New Internal Components: Every set is built using brand-new, high-quality intake and exhaust valves, valve springs, durable retainers and locks, valve stem seals, valve seats, valve guides, and pre-installed new injector cups for a proper, reliable fuel seal. Optimized Airflow (3-Angle Seats): Valve seats are cut with a precision three-angle profile to optimize airflow through the ports and guarantee an airtight seal against reground valves with inspected margins. Threaded Blow-Proof Plugs: Factory press-fit plugs are replaced with threaded, blow-proof plugs in the top of the head for leak-free peace of mind under extreme pressure. Stress-Relieved OEM Cores: Every core is Magnetic Particle Inspected (MPI) for micro-cracks, baked in a furnace to relieve material stress, and shot-blasted before precision machining begins. Optimal Deck Finish: Resurfaced to strict Roughness Average (Ra) standards to guarantee maximum gasket sealing capabilities. 100% Pressure & Profilometer Tested: Every head is pressure tested at 40 PSI and receives a documented final QC sign-off sheet measuring stem heights, valve recessions, spring pressures, and Ra finish. What’s Included in the Box: (2) Choate Remanufactured 6.6L LLY Duramax Cylinder Heads (Complete Pair) Pre-installed brand-new intake & exhaust valves Pre-installed new valve springs, retainers, and keepers (HD valve springs on Workhorse Plus) Pre-installed new injector cups, valve stem seals, seats, and guides Pre-installed O-rings (Workhorse & Workhorse Plus models only) Final Quality Control Inspection Sheet