We recently purchased a cheap $80 AMC HEI off ebay to see what and how they were so cheap. We found that the tang on the shaft wouldnt let the HEI sit all the way down and after you used the factory clamp to keep the distributor in place (KABOOM) you would eat your gears in a matter of seconds..here are the pics. So we bought another one and found it to be the same! :o
