Replacement head gaskets for your Yamaha outboard.For 50 years Sierra has been producing parts engineered to meet or exceed the specifications of marine engine manufacturers and has gained the confidence of engine manufacturers and boat builders to a point of supplying them with OEM parts. Boaters and technicians can be assured a Sierra part will fit right the first time and restore function to OEM specifications.The Sierra Engine Parts SelectorIn addition to exhaust manifolds, we offer a wide variety of other engine parts manufactured by Sierra. To see if we have the part you need, see our Engine Parts Selector, where you can search by engine make, serial number and model or year of manufacture.Mercury Outboard Head Gasket Selection ChartSIERR#InterchangeModel18-3805GLM 34950; Mallory 9-63958; Yamaha Outboard, 688-11181-02-00, 688-11181-A1-00, 688-11181-A0-00, 688-11181-01-00, 688-11181-A2-00176330918-3830GLM 34930; Mallory 9-63953, Yamaha Outboard 6H4-11181-A1-00, 6H4-11181-00-00, 6H4-11181-A0-00, 6H4-11181-A2-00491047718-3831GLM 34940; Mallory 9-63952; Yamaha Outboard 6H3-11181-A1-00, 6H3-11181-01-00, 6H3-11181-A0-00, 6H3-11181-00-00, 6H3-11181-A2-00491048518-3832GLM 34960; Mallory 9-63959; Yamaha Outboard 6E5-11181-A1-00, 6E5-11181-02-00, 6E5-11181-A0-00, 6E5-11181-01-00, 6E5-11181-A2-00491049318-3849Yamaha Outboard 695-11181-A0-00, 695-11181-A1-00, 695-11181-00-00491082418-3891Mallory 9-63950, Yamaha Outboard 61A-11181-A1-00, 61A-11181-A0-00, 69L-11181-00-00, 61A-11181-A2-00, 61A-11181-00-00, 69L-11181-01-00491061818-3894Mallory 9-63951; Yamaha Outboard 6G5-11181-A0-00, 6G5-11181-00-00, 6G5-11181-A2-00, 6G5-11181-A1-00, 6G5-11181-01-00, 6G5-11181-A3-001763309