Yamaha, 9.9-20HP - 2 1/2 Gearcase - 8 tooth spline, T8, T9.9, F9.9(4-Stroke) 2000-07, F15 (4-Stroke) 1998-, F15C 2007-, F20 (4-Stroke) 2007-, 9.9HP (2-Stroke) 1984-2009, 15HP (2-Stroke) 1984-2009