64 - 65 Dart 273
The dual point in my 65 dart has only ever had the black ones on it. The car has been in the family since 75.
I pulled a dual point from a 66 formula S in a junk yard. Also had a black cap.
I truthfully don't know if black is correct, but I can't picture it any other way. I also dont know if dual point was even an option in 64.