[9.9 - 25 hp] 3” Gearcase • 9.9hp (Bigfoot, 4 stroke) 1999-2005 • 15hp (Bigfoot, 4 stroke) 1999-2005 • 18hp Mercury 1980 - 1985 • 20hp (2 stroke) Mercury 1986-2002 • 25hp (2 stroke) Mercury 1980-2005 • 25hp (2 stroke) Mariner 1985 & Newer • 25hp (Sea Pro, Marathon) All years Thru Hub Exhaust, 10 tooth spline