Product Description

CUMMINS 3963379 OEM ROCKER LEVER COVER GASKET (ROCKER BOX GASKET) – RAM 5.9L/6.7L (2003–2024)

OE ROCKER BOX GASKET, CUMMINS LOWER VALVE COVER GASKET, 3963379, RAM 5.9 6.7 ISB, 24V DODGE CUMMINS, DIESEL ENGINE SEAL, ROCKER HOUSING GASKET

The genuine Cummins 3963379 Rocker Lever Cover Gasket provides OEM-grade sealing between the rocker lever housing (“rocker box”) and the cylinder head — the critical lower seal on a 2003–2024 Ram 5.9L/6.7L ISB 24-valve diesel engine. This direct-fit part ensures a proper seal to prevent oil leaks, keep the valve train clean, and maintain engine performance under heat and oil exposure. 

Material: OEM composite/elastomer designed for oil and heat resistance. Quantity: 1 gasket per engine. Recommended whenever servicing rocker lever housing or performing valve-cover removal. 

Cummins 3963379, rocker box gasket, valve cover lower gasket, Ram 5.9 Cummins, Ram 6.7 Cummins, ISB gasket, diesel engine gasket

Fitment / Applications

• 2003–2024 Ram 2500 / 3500 with 5.9L or 6.7L Cummins ISB (24-valve) engines — verify via VIN/ESN before purchase. 

Cross-Reference / Related Parts

• Upper valve cover gasket: CUMMINS 3954324 VALVE COVER GASKET — sold separately. 

FAQ

WILL THIS FIT MY 2003–2024 5.9L/6.7L RAM? Yes — this gasket is a direct OEM part for 2003–2024 Ram 2500/3500 with 5.9L or 6.7L Cummins ISB engines. Verify by VIN/ESN in case of earlier changes. 

 IS THIS THE LOWER GASKET UNDER THE ROCKER BOX? Yes — this gasket seals the rocker lever housing (rocker box) to the cylinder head. The upper valve cover gasket (e.g. 3954324) is separate.

 IS THIS A GENUINE CUMMINS PART? Yes — this is the genuine Cummins OEM 3963379 rocker box gasket for proper fit and long service life. 

 DO I NEED SEALANT? Follow Cummins service information. Installation is typically dry on clean, flat surfaces; sealant should only be applied where OEM specifies. 

 HOW DO I KNOW THE GASKET HAS FAILED? Common signs: oil seepage around the rocker box perimeter, burning oil smell, or oil residue on the block — if these occur, replace promptly to avoid damage to hoses or belts.