Sierra 18-0339 Thermostat Gasket Sierra Thermostat Gasket Meets or exceeds the original equipment quality Sierra part number: 18-0339 Interchangeable with the following: GLM 32820, Mallory 9-60004, Mercury 27-430062, 27-430068, 27-430067, 27-430066, 27-430065, 27-430063, 27-430061