First post here so far the site is great and very informative. I have aquired a 1969 20hp it is a step up from my 15 horse but my biggest concern is that the 15 has a slip clutch on the prop which I like since I fish in some rivers and creeks where bumping a log is not uncommon. The 20 has shear pins which I have had on previous motors and I really dont like is thre any way to convert the shear pin design to a slip clutch?