The engine and shortblock are no longer available. The original Onan engine had a 1-7/16" diameter shaft on them. You could possibly put a newer OHV engine into this machine, but you would have to add a mounting plate to raise the engine up to the original shaft height. The throttle and choke hookups would both be different and the wiring will be different. If you drive off of the flywheel side, you would have to make an adapter to bolt to the new flywheel so your drive part would bolt up to it.
Additional Info
This engine draws air past the heads and push it out the flywheel side, while every other engine craws air in the flywheel side and blows it past the heads. In order to use a different engine you must add a "heat shield" between the engine and the seat, otherwise the hot air will blow directly on the back of the seat.
