My SWAG is that they are for something like a Billy Goat, where the shaft turns a blower wheel and the whole mess is on wheels. What displacement does it seem to be? Are there any markings at all
on it? Is that a clutch on the shaft opposite the prop hub? What brand and number is the carb? More importantly than what they are, is do they run and with what size prop and what rpm? Good luck, let us now if you find out more.