Looks just like the bracket I had mounted for a while off a CB550. I mounted it to my fender by drilling holes, but even with rubber bushings and red loctite it continued to come loose and rattle so I went with a smaller light and bracket. I'm not sure what the actual light I was using was off of. It was a stanley like Hondas usually have, but I got it at a garage sale and the owner had no idea where he got it.
I think this is the best picture I have of it.