Description

Chevrolet / GMC LLY 6.6L Duramax Cylinder Head Assembly – Valves Pre-Installed – Silverado / Sierra / Kodiak / TopKick

This Chevrolet / GMC LLY 6.6L Duramax cylinder head assembly is a brand new, factory-fresh replacement for the 6.6-litre V8 turbo diesel engine used in Silverado, Sierra, Kodiak and TopKick applications from 2004.5 to 2006. It is supplied with valves pre-installed — intake and exhaust valves, springs, retainers, stem seals and guides are already fitted. The camshaft is NOT included because the LLY is an OHV engine with the camshaft located in the block, not in the head — you reuse your original in-block camshaft.

What’s Included – Fitted to the Head

• Complete cast-aluminium cylinder head casting — pressure-tested and deck surface CNC-machined
• 32 valves total per engine (16 per head) — intake and exhaust, heat-resistant
• Valve springs, spring seats and retainers
• Valve stem seals and valve guides — fitted
• Valve seats — machined and sealing-checked
• Core plugs and oil gallery plugs — installed
• Injector cups — pressed in and sealing-checked (LLY/LBZ use pressed-in injector cups)

What you transfer from your original head: in-block camshaft (stays in the engine — not part of the head), pushrods, rocker arms and rocker shafts, valve cover, head bolts (always fit new torque-to-yield bolts or ARP studs), head gasket, fuel injectors and injector hold-downs, glow plugs, intake manifold, exhaust manifold, turbocharger and any sensors or brackets mounted to the head.

Vehicle Compatibility — Model and Engine Code Detail

The Short Description lists the basic model range. The fitment below is the model-level detail needed to confirm the correct casting before ordering. The LLY casting is shared across a wide range of GM platforms, but emission equipment and glow plug type differ between LLY and LBZ/LMM applications — match the OE reference to your original head.

• Chevrolet Silverado 2500HD / 3500 — LLY 6.6L Duramax, 2004.5–2006
• GMC Sierra 2500HD / 3500 — LLY 6.6L Duramax, 2004.5–2006
• Chevrolet Kodiak C4500 / C5500 — LLY 6.6L Duramax, select 2004–2006 variants
• GMC TopKick C4500 / C5500 — LLY 6.6L Duramax, select 2004–2006 variants
• Chevrolet Express / GMC Savana 2500 / 3500 — 6.6L Duramax, select 2006 applications (LBZ-side, verify before ordering)

This cylinder head is specific to the LLY 6.6L Duramax OHV V8 diesel engine. It is NOT interchangeable with the earlier LB7 (different injector arrangement) or the later LMM / LML (different emissions equipment) without confirming glow plug type and coolant port configuration. LLY engines may require LBZ/LMM-style glow plugs when using later-production replacement heads — confirm before fitting.

OEM Part Number Cross-Reference

• Primary reference: 97779579
• Related references: 98025702, 97311546, 98055650, 98055651, 97229810, 97229808
• Engine code cross-reference: LLY, LBZ (heads are largely interchangeable with minor coolant port and sensor location differences)

Why Buy This LLY Duramax Cylinder Head Assembly

• 100% brand new — not reconditioned or repaired
• Pressure-tested to 150 psi and deck surface CNC-machined
• Cam journals machined to OEM specification (for the in-block camshaft)
• Valves pre-installed — saves valve seating and assembly time
• Correct LLY casting for Silverado, Sierra, Kodiak and TopKick applications
• Sold individually — order quantity 2 for a complete V8 engine
• Fast global shipping to port or door

More Cylinder Heads & Quick Contact

• Browse more Chevrolet cylinder heads: View our complete Chevrolet cylinder head catalog.
• Fitment check: Send us your OEM number and a photo of your original head on WhatsApp for a same-day compatibility confirmation and freight quote.