2005 Gravely PM260Z 992047 first gen production (00101-01499).Kinda scanned over the post didn't see what kind of mower this is on. That can make a difference. I recall several years ago the Kohler had a problem with the bottom main bearing due to the electric pto seeking ground and it would wiped the bottom main bearing out. Old model mowers with only one wire (hot wire) to the clutch it could do this. Is this mower that old? if the clutch windings shorted to ground it could this. Before you put a new engine on the mower I would find out why this happened. Would hate to see you ruin a new engine. Some mower manufactures put a diode in the pig tail or the wire before the pig tail. To stop the voltage spikes that a electric clutch can generate.
Mine does seem to have the diode inline, but I can confirm.