Here are a few pics of the Stihl 48 and 36

Oddly enough the bigger number is on the smaller looking engine and
the smaller number is on the bigger looking one.

The bigger one on the right as you can tell has a clutch on it.
I left it on the crankshaft to keep the flywheel from coming off.
It looks more like an RC engine than the smaller one.
When you take the clutch off, it just has a few threads on the end where the clutch was and
then there is a metal tube or sleeve that slides off the shaft and butts up against the front of the
flywheel, sorta like a spacer.
I don't see anyway to put a prop hub on this motor, but then again this would be my first conversion.
Thanks