Where is the GM Part Number Stamped?

[67BABYBLUE]

I just bought a 1967 C-10 left front fender off of a guy. He told me the fender was a genuine GM original off of a 67' pickup. This fender is as good as an NOS,I mean it's that clean,straight,and rust free. It appears to have a light blue paint on it. Looks original,not a repaint. I am just wondering,if it is an original GM part,it would have the part number stamped on it somewhere,right? Could someone help me out and tell me where that part number would be located on the fender? Any info would be greatly appreciated. I am not trying to call the guy I bought it from dishonest. It's just not everyday you find a genuine GM 67' front fender this clean for the price I paid. Thanks