Sierra 18-0398-9 Thermostat Gasket - Pack of 2 Sierra Thermostat Gasket Meets or exceeds the original equipment quality Sierra part number: 18-0398-9 Interchangeable with the following: GLM 35060, Mallory 9-60009, Mercruiser 27-33918, 27-8M2021920, OMC 385211, 312797, Volvo Penta 835417