I picked up a tow behind Giant Vac (leaf vac) today. Found it on Craigslist and it was described to be in need of work due to a "mouse nest." Owner claimed it was used on his property and not commercially and that before he parked it it ran perfectly fine. He said he parked it a year or two ago covered under a tarp and then mice made a home in it and chewed the wiring. Drove 2 hours to go look at it and it was in overall fair shape. The vac was structurally sound as can be, could just use paint. However for the life of me I could not get the motor to turn when I attempted to turn the leaf impeller. He understood my concern that it could be seized internally and basically gave it to me for next to nothing. I willingly accepted and went on my way...I know these Kohler motors quite well with having them on my Lazer Z's and Vermeer chipper. Inside the rocker cover it looks as clean as can be. Once I got it home I pulled it apart to find he was certainly correct with the mouse family living in it. Once I got the plastic shrouds off I found plenty of nesting and a live mouse as well. The ignition coils had rotted away and due to corrosion and the nest and fused to the flywheel. Likewise the stator to the back of the flywheel. Once these parts were all off the engine it rotates around perfectly fine. The engine is Kohler Model # CH20S Spec # 64567 I currently have 2 parts CH740 motors in the garage from Lazer Z's that snapped a rod. All the other parts are there and were working before the internal damage. After looking through parts schematics I see most of the parts are the same but am not 100% certain that all of them are interchangeable. While I would be glad to buy all new parts for this unit...I want to be sure it runs properly first. I dont want to dump a ton into parts and then end up just putting a new motor on it all together if this one isint solid. The stators are both part number 237878-S so I know they can be used. The old flywheel is rusted to hell so I could wire wheel it but if the one on the CH740 would work I would use that. Also the coils are 24-584-45s which I think was succeeded to a newer part number. Anyone know if it the flywheel and coils would be interchangeable? I cant find the spec number on the CH740 as the tag rubbed off with time. Not sure if its anywhere other than on the plastic covers. On a side note, anyone know what the crank size is on this motor? I cant find it anywhere online. In the event I were to replace the motor or shortblock id probably up the power to a 25 or 27hp. Thank you for your time!