I didn't get much time in the garage tonite but I did manage to get the aluminum duct off the 1650 only to find that it is not my noise. I stuck the muffler back on, fired it up, still makes the noise. I didn't get a chance to address the iso mounts or the flywheel shroud contacting the cradle but those are next on the list. Still really hoping the 13 fin 16hp kohler isn't in need of a rebuild. Oh, and since I've gotten rather used to removing the heavy ol k341, when I pull it to ease the installation of iso mounts I will be also checking the end play. Should the pto clutch be removed when checking end play?