[mot]

here is what the difference is
the early 30 lamps are completly different than the later ones
the bulb mount is different
the lens is different
the rim is different
the reflector is different
the early one takes a screw through the inner mounting bracket ,which holds the reflector
the riveted one just rivets the bulb holder
and the reflector slips over the holder
the early 30 rim has no hole in it to secure the rim,it just snaps in place
the later one has a hole and screw to hold it to the shell
the early lens has Top on the top of the lens
so as you can see they are totally different in every way
the arms although different are interchangeable
tom