NOS? GM Grill

[mgkgmc]

I just picked up this 69/70 grille from a guy on craiglist it came with this box end. He tells me he got it in a trade the box got damaged from sitting in his back yard and he said it is NOS. Is there anyway to verify if its real GM Grille. I heard that some of the stuff from GM is a certified GM repro parts or is this a real GM part? The box has a GM part number 3985054.