Tango Cub question:

I just noticed our more or less stock Tango cub (the CAP deal with toe brakes) has an extender between the prop and the crank. Is this required, or even legal? Without it there would still be maybe a half inch clearance to the starter casting, which ought to be plenty . . .

That is probably the adapter for the McCauley prop on the O-235-C1 engine.