I'm not absolutly sure, but I think they are the same part on a bug and bus . . . Seems like there are two different ones (one had one mounting screw and another had either two or three screws . . . I think . . . I get dangerous when I think), but they were used in different years, and whatever was used on the bugs was used on the buses of the same year.  My bus is a 73, and I've got 68, 74 and 75 Beetles sitting in the yard.  I'll take a look tomorrow evening and see what those look like.