Sierra International 18-4306 Powerhead Gasket OMC 394546 Sierra Powerhead Gasket Set Does not include Head Gasket Sierra part number: 18-4355 Interchangeable with the following: GLM 39330, Mercury 27-78028A78, 27-55306A75, 27-55306A74, 27-55306A73, 27-55306A72 Fit specific, check part numbers to ensure proper fit