I've seen both masts but tube seems to be more common. Bases I've seen in original cars including my own are grey. Green is the more common hook color but I have seen gray also. If I remember correctly, the hook for rubber bumper cars is the same shape but does not have the stamped part number. Rubber bumper car hooks I've seen were green too.
I don't think hook color had anything to do with early vs late but instead a different supplier. My August 70 car has the tube shaft......