I am part out a Honda GX670 engine that was a repower for a John Deere 420 lawn tractor.  It is up to you, and you alone, to determine if this part fits your engine.

Honda GX670 engine crankshaft.  Beautiful shape as shown and the slotted PTO mounting end is 1 7/16" in diameter to utilize the standard Onan clutch used on the 316 Onan, 318, and 420 models among others.  Thanks.