Sierra International 18-2831-9 Thermostat Cover Gasket - Pack of 2 Sierra Thermostat Cover Gasket Meets or exceeds the original equipment quality Sierra part number: 18-2831-9 Interchangeable with the following: Barr MC472747590, GM 31430, Mallory 9-60012, Mercruiser 27-475901, 27-47590, 27-47590B1