Re: 1960 18 hp. Fastwin, bad clutch dog
The 25 hp gearcases' up to the mid 70's will fit. This will give you the advantage that the 25 has a much stronger gearcase casting. I have a 57, and 58, 18 hp. I run 25 gearcases' on both. There is also a heavy duty gear, and clutch dog set for the 25 case, if still available.