The color of the clutch the cylinder will have a mark on the side of the m-30 I think it is it will either be an a. 1 .2. b. or 3c... Also all have a v. The spark plug and carb are different on the 35 mph.
The cases correspond to the cyl with a base skirt groove that joins the case induced intakes. They also have a corresponding # on the case.
Red brown clutch encarwi 8s a or 1 cyl and 11or10 on the case Bosch150w plug.