New Pair Chevrolet GM Duramax 6.6 Diesel Cylinder Heads LB7 2001-2004.5 W/ Head Gasket Set and Bolts

Revitalize your 2001-2004.5 GM Chevrolet Duramax 6.6 LB7 diesel engine with a pair of high-quality aftermarket cylinder heads. These heads arrive ready for installation, featuring pre-installed injector sleeves. The package also includes a complete head gasket set and bolts for a seamless upgrade.

Key Features of Duramax 6.6 LB7 Cylinder Heads:

• Compatibility: Designed specifically for 2001-2004.5 GM Chevrolet Duramax 6.6 LB7 diesel engines. Check the 8th digit of your VIN to confirm compatibility (it should read “1”).
• Injector Sleeves: These come pre-installed to save time and enhance performance.
• Precision Machining: State-of-the-art Serdi or Sunnen equipment ensures accurate seat and guide work. The Rottler CBN machine creates the exact RMA finish required during resurfacing.
• Sealing Performance: High-quality valve seals ensure a secure seal between the valve and seat, with each valve vacuum-tested for reliability.
• Quality Assurance: Every head undergoes thorough cleaning, inspection, and pressure testing to guarantee long-lasting performance.

• Included with Your Purchase: Complete head gasket set and bolts.

Why Choose Our Cylinder Heads?

A cylinder head is crucial for the efficiency and performance of your engine. It contains the intake and exhaust valves, spark plugs, and fuel injectors, which are vital for the engine’s operation. Our heads are designed to handle the extreme pressures and temperatures within the combustion chamber, ensuring optimal engine performance.

Signs You May Need a New Cylinder Head:

1. Weak Engine: Poor fuel efficiency, sluggish acceleration, or difficulty climbing steep inclines may indicate a cracked cylinder head.
2. Oil Leakage: Puddles of oil under your vehicle can signal a leaking cylinder head.
3. Coolant Leakage: Overheating warnings or coolant puddles may indicate a cracked head.
4. Engine Misfires: Repeated engine failures or trouble starting may be due to cylinder head damage.
5. Smoke: White smoke from the engine suggests severe cylinder head failure.

Heavy Duty Parts Company – Core Returns Policy

Effective December 17, 2025

At Heavy Duty Parts Company, core returns are essential to our ability to provide high-quality, cost-effective cylinder heads. Returned cores supply critical components—such as keepers, springs, and retainers—that are vital to proper engine performance and allow us to maintain OEM-level quality.

No Upfront Core Charge

Unlike many suppliers, we do not charge a core fee upfront. Instead, we rely on customers to return their used cores within the required timeframe.

Core Return Requirements

• Cores are due within 30 days of the purchase date

• If a core is not returned within 60 days, the product warranty is void

• Unreturned cores will be charged as follows:

  • Cylinder heads under $600: $200 per unreturned core

  • Cylinder heads $600 and above: $400 per unreturned core

Customers needing additional time may contact us to request an extension. Approved extensions will prevent core charges from being applied.

Core Return Process

Cylinder heads are shipped with prepaid core return labels included in packets attached to the outside of each box. If labels are missing, customers should contact us for replacements prior to returning the core.

Core Eligibility

Some cylinder heads do not require a core return. In certain cases, core requirements may be waived at our discretion.

Why Core Returns Matter

• Reused core components help maintain OEM-quality standards

• Core returns allow us to keep pricing competitive

• Recycling cores supports sustainability by reducing waste and conserving resources

This policy applies to all purchases made on or after December 17, 2025.

Send Back All Components

To ensure the quality and integrity of our remanufacturing process, we ask that you return all components that were originally included with your new cylinder head. This includes items such as:

• Rocker arms
• Camshafts (if applicable)
• Any other hardware that came with your purchase

Easy & Free Core Return Process

• Each purchase includes a prepaid core return label in a plastic sleeve on the box.
• Simply pack your core with all included components, attach the label, and drop it off with the carrier—no extra cost to you.
• Returned cores undergo inspection and recycling, ensuring maximum efficiency.

Customer Partnership & Sustainability

By returning your core and its components, you help maintain a reliable supply chain, ensuring we can continue offering top-quality products at the best prices. This process not only benefits your wallet but also contributes to a greener and more efficient automotive industry.

We appreciate your support in keeping our business and the industry running smoothly!

GM Authority

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