BTW did you by chance look at the magnets on both flywheels ????
The 18hp has a metal sleeve covering the magnets, I really want to bother trying to take that out to look as it might not stay when I put it back in. Seems like a good idea that they used that though as it keeps debris out of the magnets, and keeps them in place if they come loose and you don't destroy your stator. I also compared stators side by side, both identical, both i assume 20 amp as that is what my engine came with. And they appear to have the same gauge wire and number of windings.