This listing covers the Alliant Power new Grade B (1.00mm) multilayer steel (MLS) cylinder head gaskets for the 2001–2016 GM 6.6L Duramax, Alliant part numbers AP0048 and AP0051. Alliant’s head gaskets seal the cylinder head to the engine block to help contain combustion pressure, coolant, and oil passages.

Features & Benefits

• New Alliant Power Grade B Duramax head gasket, 1.00mm thickness (Alliant P/N AP0048 / AP0051)
• Alliant lists AP0051 as the right (passenger-side) gasket: 1.00mm thick, 105.4mm bore, multilayer steel with FKM bead
• Sold individually; match the side and grade of the gasket you are replacing
• Direct replacement for GM 12637786 (AP0048) and GM 12637789 (AP0051)
• Backed by Alliant Power’s 24-month, unlimited-mileage warranty

Application

• Chevrolet Silverado 2500 HD / GMC Sierra 2500 HD (2001–2016)
• Chevrolet Silverado 3500 / GMC Sierra 3500 (2001–2006)
• Chevrolet Silverado 3500 HD / GMC Sierra 3500 HD (2007–2016)
• Chevrolet Silverado 2500 HD Classic / 3500 Classic and GMC Sierra 2500 HD Classic / 3500 Classic (2007)
• Chevrolet Express 2500 / 3500 and GMC Savana 2500 / 3500 (2006–2016)
• Applications per Alliant Power for AP0048 and AP0051

Always verify fitment against your VIN, engine, and OE part number before ordering.

Cross-Reference / Replaces

• AP0048 — General Motors: 12637786, 19301791, 97188468, 97288227, 97309563; Mahle Clevite: 54584; Elring: 541.792
• AP0051 — General Motors: 12637789, 19301794, 97188465, 97288224, 97309560; Mahle Clevite: 54581
• Alliant Power: AP0048, AP0051

Warranty: Alliant Power’s standard warranty: 24 months with unlimited miles/hours on installed parts (Alliant Power warranty policy, rev. Aug 2025).