Color of panel beneath tailgate -- '72 K20

[Stocker]

Was at the shop yesterday, got a question about the narrow panel (back of the bed?) that runs side-to-side just below the tailgate and above the bumper. Should it be body color, or black? Right now mine looks like a dull black (primer?) and nobody knows what it should be. I can't remember, not that I ever paid much attention to it -- it's fairly well hidden. I looked at pics here on the site but couldn't tell for sure if it's black or just in the shadow.