I have just finished a total resto on a Shadow that came from a well known collection in the states, and this has one of the Miller 6 1/2 inch headlamps to suit the US market. The shell is identical to the more common Miller type except for the rim section at the very front, this to suit the split clamp type of rim as has been mentioned earlier. The chrome rim is not a genuine Miller one although I believe I have seen them available on EBay.........If you want to go to that expense. Anyway, the rim tapers outward from the shell, thus allowing the larger sealed beam as originally installed. Whereas the other more common 6 1/2 inch Miller shell, well it's chrome rim is a completely different shape, and tapers inward with a nice radius to suit a Miller glass which fits through the rim with a hole diameter of about 6 inches. The actual overall total width of the glass is 6 1/2 inches. The shell of the US variant has a cut out in the very front of the steel rim at about the 11 o'clock position when looking from the front, and this is to locate on one of the 3 locating tangs that the sealed beam unit has. I have found this is pretty much the same as the Lucas pre- focus type of lamp/reflector unit as well, and this is what I have installed in this headlight assembly, as I am not sure of the availability of the sealed beam lamp for a 6 volt system, these days. Cheers.......Greg.