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Selecting the right head gasket for GM Duramax 6.6L Diesel Engines

Challenge - Getting the correct Head Gasket

A powerful and reliable engine, the Duramax 6.6L diesel engine is found on many Chevrolet and GMC ¾-and 1-ton trucks and vans. With a confusing array of engine variations and head gasket design, selecting the right head gasket can be a challenge.

Multi-layer steel (MLS) construction is the one common characteristic of all five OE head gasket versions. GM has used two different MLS designs – one for 2001-2004 models and another for 2005 and newer engines. Within each of these base designs are three additional gasket grades or thicknesses. To further complicate matters, technicians must also choose from two separate gasket thicknesses for engines that have either been over-bored or over-bored and deck milled.

To help identify these gasket variations, GM uses a hole and slot system which is located at front end of the head gasket.

Solution – Fel-Pro® PermaTorque® MLS Replacement Head Gaskets

With two designs of PermaTorque MLS head gaskets that cover all grades, Fel-Pro has taken the guesswork out of selecting the right head gasket for the Duramax 6.6L diesel engine. This streamlined lineup of gaskets not only helps the technician save time and avoid confusion, but it also incorporates exclusive features that address the unique requirements of the aftermarket repair environment. Fel-Pro has taken the guesswork out of selecting the right head gasket

FEL-PRO #26401PT (LH) AND 26402PT (RH)

Accomodates all model years as well as over-bored blocks and OE grades A, B and C.

Fel-Pro 26405PT (LH) and 26406PT (RH)

A .010" thicker gasket accommodates blocks that have been overbored and deck milled (all grades and model years).

Applications Covered*

Year Make/ Model
2003-2007 Chevrolet Kodiak/GMC TopKick C4500/C5500
2006-2016 Chevrolet Express/GMC Savana 2500/3500
2009-2016 Chevrolet Express/GMC Savana 4500
2001-2016 Chevrolet Silverado/GMC Sierra 2500 HD
2007 Chevrolet Silverado/GMC Sierra 2500 HD Classic
2001-2006 Chevrolet Silverado/GMC Sierra 3500
2007 Chevrolet Silverado/GMC Sierra 3500
2007-2016 Chevrolet Silverado/GMC Sierra 3500 HD

*For full application listing, please visit

The Fel-Pro Advantage

Fel-Pro’s head gaskets for GM’s Duramax 6.6L diesel engine feature:

PROPRIETARY COATING -- Exclusive coating helps withstand rougher sealing surface finishes up to 80 Ra

UNIQUE COMBUSTION SEAL -- Exclusive LaserWeld stopper layer technology reduces gasket damage from blow out and helps ensure a stronger combustion seal

MULTI-LAYERED STEEL CONSTRUCTION -- Multiple layers of stainless steel maintain sealing stress and accommodate head lift

SUPERIOR SEAL -- Precise embossed sealing beads at all vital areas to eliminate leak paths

HANDLES EXTREME ENGINE CONDITIONS -- Engineered and manufactured to inhibit over-compression of embossments to maintain a superior seal under peak combustion pressures and temperatures

DESIGNED FOR IMPERFECT SEALING SURFACES -- Engineered and manufactured specifically for the repair environment to help seal imperfect sealing surfaces


Learn more about Fel-Pro quality gaskets that are specifically designed for the repair environment, find your car part, or find where to buy your auto part today.

The content in this article is for informational purposes only. You should consult with a certified technician or mechanic if you have questions relating to any of the topics covered herein. Tenneco will not be liable for any loss or damage caused by your reliance on any content.

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