Dave,
I sell a replacement one that looks real close to the OEM "B" lamp. The original ones rust so bad sometimes they're just unrepairable. The one I offer comes w/new circuit to the headlight sw in the ammeter box, is 6V, & bolts to the OEM bracket too! I have the same one on my "B". It's not an original, but it's darn close! Drop me a line if you decide you want one........ Steve B.