I think my point was missed. I have owned my car since 1982. At that time, there was not even information regarding "X" codes on the trim plate, much less the rear bulkhead. It was fun finding the X3 marking where it had been hidden since 1968! It is really just another of many pieces of the puzzle documenting the car, most of which have been identified long after I bought it. All I knew for certain at the time was that "DZ" was the 302.