Product Description
FLEECE FPE-61-10002-P 2004.5-2005 FACTORY LLY DURAMAX CYLINDER HEAD (PASSENGER SIDE)
Restore your 2004.5-2005 6.6L LLY Duramax with the FLEECE FPE-61-10002-P Factory LLY Duramax Cylinder Head (Passenger Side). Built by Fleece Performance Engineering in their Freedom Series line, this new-casting cylinder head is thoroughly cleaned, machined, pressure & leak tested, and assembled with new valve guides, springs, and seals—giving you high-impact reliability, strong sealing, and a direct replacement for the factory passenger side head.
This head utilizes precision ground stock-valves with a 45-degree seat angle and a multi-angle valve job to improve combustion efficiency and durability. It’s ideal for daily-driven trucks, heavy towing rigs, or any 2004.5-2005 LLY owner looking for a reliable top-end solution.
Key Features:
- New casting Freedom Series cylinder head for 2004.5-2005 6.6L LLY Duramax
- Passenger (right) side head engineered to meet or exceed factory specification
- New valve guides, valve springs, and valve seals pre-installed
- Precision ground stock valves with 45° seats
- Multi-angle valve job for improved flow and sealing
- Decked, pressure & leak tested to ensure durability
- No core charge required — keep your old head or scrap it
- Backed by 1 Year Limited Parts Warranty
Fitment
Engine: 6.6L Duramax LLY
Model Years: 2004.5, 2005
Position: Passenger Side (Right)
- 2004.5 Chevrolet Silverado 2500HD 6.6L LLY Duramax
- 2005 Chevrolet Silverado 2500HD 6.6L LLY Duramax
- 2004.5 Chevrolet Silverado 3500HD 6.6L LLY Duramax
- 2005 Chevrolet Silverado 3500HD 6.6L LLY Duramax
- 2004.5 GMC Sierra 2500HD 6.6L LLY Duramax
- 2005 GMC Sierra 2500HD 6.6L LLY Duramax
- 2004.5 GMC Sierra 3500HD 6.6L LLY Duramax
- 2005 GMC Sierra 3500HD 6.6L LLY Duramax
Note: This listing is for one passenger-side cylinder head. If you are doing a full head swap, you may want the matching driver side head as well.
Recommended Fleece Cross-Reference / Related Parts
- Driver-side matching head: FLEECE FPE-61-10002-D 2004.5-2005 FACTORY LLY DURAMAX CYLINDER HEAD (DRIVER SIDE)
- Passenger head for next gen LBZ/LMM: FLEECE FPE-61-10003-P 2006-2010 FACTORY LBZ/LMM DURAMAX CYLINDER HEAD (PASSENGER SIDE)
- Driver head for next gen LBZ/LMM: FLEECE FPE-61-10003-D 2006-2010 FACTORY LBZ/LMM DURAMAX CYLINDER HEAD (DRIVER SIDE)
Why Choose Fleece Freedom Series for Your LLY?
The Fleece Freedom Series heads are produced in a dedicated racing-engine facility, giving you precision-machined parts, new valvetrain components, and stringent quality testing. They’re built to handle the demands of real trucks—whether heavy towing, high mileage, or harsh duty cycles—making it an ideal top-end solution for your LLY Duramax.
Installation Notes
- Always use the correct head gasket: Fleece recommends GM 12637788 (Grade C, Right) and GM 12637785 (Grade C, Left) for LLY applications.
- Use new head bolts or head studs and follow the OEM torque sequence and specs.
- Ensure the block deck surface is clean and flat before installing.
- Professional installation is recommended for modern common-rail diesel engines.
Specifications for FLEECE FPE-61-10002-P
| Attribute | Value |
|---|---|
| Brand | Fleece Performance Engineering |
| Part Number | FPE-61-10002-P |
| Engine | 6.6L Duramax LLY (2004.5-2005) – Passenger Side |
| UPC | 670875716612 |
| GTIN | 670875716612 |
| Series | Freedom Series Cylinder Head |
| Casting | New casting, machined to OEM spec |
| Valvetrain | New valve guides, valve springs, valve seals; stock-style valves with 45° angle seats |
| Testing | Cleaned, decked, pressure & leak tested |
| Core Charge | None – no core charge required |
| Shipping Info | Approx. 32-45 lb ship weight; boxed size approximately 15″ x 12″ x 23″ as listed on product page |
| Cross Reference / Related Part Numbers | Matching driver side FPE-61-10002-D; next-gen LBZ/LMM heads FPE-61-10003-P/D |
| E-Codes | Not specified |
| Prop 65 | WARNING: Cancer and Reproductive Harm – www.P65Warnings.ca.gov |
FAQ
Is the FLEECE FPE-61-10002-P head a direct replacement for my stock LLY passenger head?
Yes. This head is designed specifically for the 2004.5-2005 6.6L LLY Duramax passenger side. It meets or exceeds OEM specs and is a direct replacement for the factory unit.
Do I have to send in a core or pay a core charge?
No. This Freedom Series head is offered with no core charge required, making the installation process easier and saving cost.
Which head gasket set should I use when installing this head?
Fleece recommends GM 12637788 (Grade C, Right / passenger) and GM 12637785 (Grade C, Left / driver) head gaskets for LLY applications.
Can I install this head if I’m planning performance upgrades or towing applications?
Absolutely. This head is ideal for daily driving, heavy towing, and mild performance upgrades. If your build has aggressive tuning, high boost, or substantial modifications, ensure supporting components (head studs, gaskets, tuning) are upgraded accordingly.
Should I replace both cylinder heads at the same time?
While you can replace just the passenger side, many owners choose to replace both sides at once when doing major top-end service. Matching driver side head ensures both sides have the same new casting, machining, and valve components.
