Since I can't afford an original hub lamp, I bought one of Greg Barron's replica lamps at a recent annual meet. Since the hub of my Expert was too large, the lamp stayed in its box for a few years.
Well, it fit on the Light Roadster I've been riding for a year!
I have a couple of tips to offer for those who have one of these replica lamps.
For a quick manner of mounting, I (loosely) wrapped thin strips of leather around the hub for the sheet metal lamp to ride on. This is temporary since I'm installing it for an exhibit tomorrow.
The first time I rode around town on it, it made quite a rattling sound. Long story short: the various pieces of glass are loosely held by sheet metal pieces. The glass was rattling around while riding. Solution? Using a toothpick, I dribbled small amounts of liquid contact cement in few spots in the edge of each glass. The clear front glass was also in need of such treatment. Not all the way around the glass.
No offense, Greg, but I also turned the RBR label around so the blank side is seen. Makes it look more 'authentic'.