My foolproof method of checking for originality involves hitting the fender with a ball peen hammer. If it dents instead of cracking, I can tell at least that it is aluminum. Next I take a hacksaw and cut a pie shaped wedge out of the fender area. I then measure the thickness of the aluminum. If it is at or under .025" then I know its orginal. If over .025" it has to be a Kirkham, Shelby, or Kimmon. The last time I tried this test, I was shot and killed by a slightly aggitated Cobra owner