It's an AV7 but I don't remember a woodruff key, aside from the clutch. Sending the rotation via the back wheel makes sense.
I am in need of a new rear hub, couple sections broke off. For now, the front wheel is on and the swing arm is ratchet strapped to a stool. Trying to get it running by turning it over with a drill but every time the engine catches, the flywheel nut or the nut on the clutch comes loose (tried both sides). I could probably put the rear have and chains back on.