Sierra International  18-2805-9 Block Cover Gasket - Pack of 2 Sierra Block Cover Gasket Meets or exceeds the original equipment quality Sierra part number: 18-2805-9 Interchangeable with the following: GLM 31920, Mercury 27-85490-2, 27-856729, 27-854901, 27-85490, 27-78029, 27-74708, 27-55307