Mercury/Mariner, 9.9-25HP - 3 Gearcase - 10 tooth spline, 9.9HP Bigfoot (4-Stroke) 1999-2005, 15HP Bigfoot (4-Stroke) 1999-2005, 18HP 1980-85, 20HP (Mercury 2-Stroke) 1986-2002, 20HP (Mariner 2-Stroke) 1985-, 25HP (Mercury 2-Stroke) 1980-2005, 25HP (Mariner 2-Stroke) 1985-, 25HP Seapro/Marathon, 25HP (Force 3-Cyl) 1995-98