2004.5-2005 LLY Duramax Premium Stock Plus New Cylinder Heads (RH & LH Set)

Restore factory performance and reliability to your 2004.5–2005 LLY Duramax 6.6L with these brand-new Premium Stock Plus cylinder heads. Designed as a direct replacement for factory heads, these new castings eliminate the uncertainty associated with remanufactured cores while delivering the durability, airflow, and performance required for stock and mild performance applications.

Each cylinder head is precision machined and assembled using premium components to ensure proper sealing, valvetrain stability, and long service life. Whether you're replacing damaged cylinder heads or building a fresh engine, these Premium Stock Plus heads provide a dependable foundation for your Duramax.

Key Features

• Brand-new LLY Duramax cylinder head castings
• Precision machined and assembled
• Diamond honed valve guides
• Unshrouded valves for improved airflow
• High-strength, heat-treated iron-based valve guides
• Premium nickel-based, non-magnetic valve seat inserts
• Multi-angle valve job
• New valve springs installed
• Assembled and ready for installation
• Direct replacement for factory cylinder heads
• Ideal for stock replacement or mild performance builds

Premium Stock Plus Construction

Built from all-new castings, these Premium Stock Plus cylinder heads are engineered to provide exceptional reliability and performance. Each head undergoes precision machining and assembly processes to ensure consistent quality, proper sealing, and optimal airflow.

By starting with brand-new castings, these heads eliminate concerns associated with used cores, cracks, repairs, or previous heat cycles, providing a fresh foundation for long-term engine durability.

What's Included

• Left and right new LLY cylinder heads
• Fully assembled and ready to install

Not Included

• Gaskets
• Head bolts
• Injectors
• Installation hardware

Vehicle Fitment

2004.5–2005 GM Duramax LLY 6.6L

• Chevrolet Silverado 2500HD
• Chevrolet Silverado 3500HD
• GMC Sierra 2500HD
• GMC Sierra 3500HD

Why Choose These New LLY Cylinder Heads?

• Brand-new castings with no core history
• OE-style fit, function, and performance
• Premium valvetrain and machining upgrades
• Ideal for engine rebuilds and cylinder head replacement
• Built for long-term durability and dependable operation

Core Return Information

Sold as a matched left and right pair.

To receive full core credit, a good, reusable pair of LLY cylinder heads must be returned. Cores must be free of cracks, excessive warping, or severe damage. Core returns are required within 90 days of purchase.