Is this an AMD tail panel??

I got a 68 tail panel with a car & parts I bought. Has any other manufacturer other than AMD made these? First off its grey instead of black (The previous owner could have primed it, it seems like an epoxy or something..will not wipe away with thinner). The only numbers/stamping I could find is "AP 42" stamped on the top in the center. Just wanting to check to see what I have. Pics below.
Jason

I thought Sherman and associates also had a brief run of 68 Charger panels as well.