MAHLE 55026 Right Side (Passenger) Cylinder Head Gasket – Grade C 1.05 mm (5458X series) for 2001–2016 GM 6.6L Duramax

The integrity of your Duramax starts at the head gasket. The MAHLE 55026 is a premium multi-layer steel (MLS) right-side cylinder head gasket engineered specifically for 2001–2016 GM 6.6L Duramax engines (LB7, LLY, LBZ, LMM, and LML). This is the updated OE-style Grade C gasket (1.05 mm / ~0.041" thickness) that supersedes the earlier 54582.

Key Features

• Multi-Layer Steel (MLS) construction with Combustion Load Limiter / Wave-Stopper technology that dynamically adapts to changing cylinder pressures and loads
• Precise Grade C 1.05 mm thickness for correct combustion chamber volume on standard-bore engines
• Designed to handle the extreme thermal cycling, high cylinder pressures, and heavy towing/boost conditions common to Duramax applications
• Direct-fit replacement that meets or exceeds original equipment form, fit, and function
• Stamped for side identification

Specifications

• Part Number: MAHLE 55026 (supersedes 54582 / 5458X series)
• Side: Right / Passenger
• Thickness / Grade: 1.05 mm – Grade C
• Material: Multi-Layered Steel
• Bore: Standard bore
• Sold: Individually (left-side gasket sold separately)

Fitment

2001–2016 Chevrolet Silverado / GMC Sierra 2500HD & 3500HD with 6.6L Duramax

• LB7 (2001–2004)
• LLY (2004.5–2005)
• LBZ (2006–2007)
• LMM (2007.5–2010)
• LML (2011–2016)

Important Notes

• For standard bore cylinders only
• Cylinder head bolts are not included — always install new torque-to-yield (TTY) bolts or upgrade to high-strength head studs during installation
• Verify required gasket grade/thickness against your original gasket or machine shop measurements before ordering

This is a high-quality, OE-grade sealing solution trusted for both stock and moderately modified Duramax engines. Pair it with proper torque procedure, new fasteners, and careful surface preparation for a reliable, long-lasting repair.