The problem I seem to have is finding one with a cent. clutch.... I have an 18cc featherlite motor now (needs a new piston ring), but it does not come with the clutch. Would the clutch assembly from a 21/24cc engine fit, or would I need the crank too. I would guess if they come with a clutch that the crank is a bit different, or maybe just the adaptor for the flex shaft is different.