Thanks for the info. However when I look at the back of the two the detail is identical right down to the shape and finish of the welded in bits and threaded parts. If an aftermarket copy is is very good.
I also have two of the earlier non enclosed type and they do not have the indent feature. From what I can find the GS went to the enclosed in 54 and the A10 in 53. I always assume refs are for model year but who can really say. Were any of the earlier open types indented for the light? Was it the adoption of the rectangle shaped light that lead to the indent? The indent keeps the top of the light inline with the top of the mounting. Any info would be appreciated.
PS thanks Irish Swede and Slowlearner for comments while I was posting.