Mercury, 4-6HP - 12 tooth spline, 4HP (2-Stroke) 1987-, 4HP (4-Stroke) 1999-, 5HP (2-Stroke) 1987-, 6HP (4-Stroke) 1999-, , Tohatsu/Nissan, 4-6HP - 12 tooth spline, MFS4, M5B (2-Stroke), MFS5, MFS6