NOT TO CHANGE THE SUBJECT BUT I HAVE A 68 SS427 L72 CAR. IT HAS 15 INCH STEEL WHEELS WITH WHAT LOOKS LIKE A PF CODE AROUND THE VALVE STEM. DOES ANYONE KNOW IF THERE WAS A 15 INCH WHEEL OPTION FOR THESE CAR? ALSO HOW CAN YOU TELL IF THE TRANS IS A M21 OR M22 WITHOUT TAKING IT APART? ALSO IT HAS A DN CODE ON THE REAR. ISNT THAT A 410?