The 2001-2004 GM 6.6L Duramax Cylinder Heads play a crucial role in your truck's rotating assembly, helping determine compression and working with the camshaft and valvetrain to shape the engine's power and torque curve. This becomes even more important when upgrading or modifying your engine, as the stock head often falls short in high-performance applications. Fortunately, we offer a range of aftermarket cylinder heads designed to significantly improve airflow, allowing your Sierra/Silverado 2500HD/3500HD to harness more power and support various performance upgrades. Unlock your engine’s full potential and let it breathe easier with any of the aftermarket cylinder heads available at Alligator Performance! Check out our selection of Oil Pans, Valve Covers & Accessories for further performance and reliability!GM Duramax Fitments: 2001, 2002, 2003, 2004 GM 6.6L Duramax.Submodel Fitments: WT, Custom, LT, LTZ, High Country, 1LT, 2LT, Pro, SLE, SLT, AT4, Denali.Some exceptions apply, please see individual product pages for specific fitments.