Doc, Chuck(ThumperSRT-6) has a Karmen 62 bought directly from Rudy. He tested it with a magnet and nothing. Tested it on a few other parts and stuck, but not to the SC pulley. That's weird considering it should by all means stick to hardened steel. Hopefully that clears up some confusion. But you're correct about the backing plate being the problem for the Karmen pulleys not bought directly from Rudy. RED DOG has a valid concern about them getting an "off" batch piece. They definitely look different and the failed pulleys have noticeable friction marks on the rivet heads.