I think they were both gray and black and it was a MFG thing. I am guessing it was a mfg that discontinued making them while the one that made the black continued to supply. You typically see the gray on 67/68 cars but have also seen black in a unmolested context on the same years. . The gray are very rarely seen relatively speaking which makes me think it was a MFG thing given so many more genuine black ones are seen .