Well maybe they changed them at some point, but here is my 67 dart OEM,
Here is the aftermarket replacement.
MMC claimed that the foam between the 67 convertible rear tach strip and the body were always white, my 67 dart were black, and when I got some sheet metal off a 68 or 69 that happened to have that same location the foam tape was also black.
Alan's is black, so I would have to say black is OEM at least in 67.