9.9 - 20 hp] 2-1/2” Gearcase • 9.9hp (2 stroke) 1984 & Newer • 9.9hp (4 stroke) 2000-2003 • 12hp 1985-1988 • 15hp (2 stroke) 1985 & Newer • 15hp (4 stroke) 2000 & Newer • 18hp (2 stroke) 1985 & Newer • 18hp (4 stroke) 2001-2008 • 20hp (4 stroke) 2007 & Newer Thru hub exhaust, 14 tooth spline