your right, I have a 1982 or 83 18hp and its very tired, mu buddy has a 1989 20hp that's mint other it hit a rock and smashed the lower end, I took a chance today and bought his 20, It has bigger bolt that hold the lower end on and his had dowel pins and mine did not so all I did is drill my lower holes to 3/8 and it fit on and works perfect.