The only identifying marks you may find on an original grille would be a black date ink-stamp. This would typically be on either of the sides on the vertical flat spot.
Original grilles were assembled with the small top tubular rivets, these are usually black or natural. Ford serviced a '65 grille that had large stand-up rivets which do not match the assembly line style. For whatever reason, folks over the years assumed this was correct. The top end tabs and vertical supports were black and then installed with the rivets. The grille color should be a bluish gray, with variance through the production year. Some very early 64.5 cars may have had more of a silver grille color.