I have a 1953 3100 that has two holes above the vent window and two holes below the vent window. Does anybody know what these could be for? There are identical holes on the driver's door. They may be for a mirror, but I can't find anybody selling a mirror that would be supported this way. Here is a link to a picture showing the holes: http://picasaweb.google.com/barthhc/DoorHoles#5485715672943627074