I have a Farmall A, I am looking for a magneto. I'm thinking one rebuilt h4 is basically the same thing as any other h4, until I look on Ebay. One says it is for diesel engines, another says it has a counter clockwise rotation and is for "T14, TD14, I6, O6, T6..etc", but the A, AV, B, Bn, C are not listed. What's the deal? Is an h4 mag an h4 mag, or are there different types of h4 mags? My old mag, by the way, was disassembled by a nincompoop before I took possession of the tractor and pieces are gone. I am pretty sure it runs clockwise, unless the ninnyhammer that took it apart put it all (mostly all) back in backwards?