Dittos to what high plains said.[8D]

I can confirm possibly not exactly the same but with the small general aviation engine the Continental C-85 typical of Cubs, airnockers and Ercoupes etc. that there are six possible propellor/crankshaft orientations possible due to the bolt pattern. When the McCauley metal prop is used one of those positions there will be a very noticible vibration in flight and it can be eliminated simply by rotating the prop to any of the other five positions.

John