70 challenger bumper part number markings

[MKA]

Is there a part number or other stamp on the bumpers to confirm they are original?

In process of purchasing a rechromed rear bumper for a 70Challenger  marked as original.   Since every original part seems to be marked was wondering where to look to confirm.    I have a core 70 bumper I bought off another member but I don't see any marking.  Could be covered with dust or otherwise concealed, but if it's there where do I look?   I assume it would exist. 

TIA

[anlauto]

I would be surprised if there was, I've never heard of such a thing