36084F, Lucas part # CZU27 according to the parts lists. Unmarked scale, black face.
See here for the CZU range:
http://www.brightsparkmagnetos.com/library/Parts%20lists/Lucas%20motor%20cycle%20parts%201936-57/C01-03%20Ammeters.pdfBizarrely, 12-12 scales were used on machines of all sorts when systems went to 12v. 15-15 I've only seen now and again, 30-30 and 45-45 were also quite common on cars.
I say 'bizarrely' because at 6v an 8-8 scale will be at max needle deflection at 48W load, which although fairly academic in practical normal use, isn't much. You're off the scale with a 45/40W globe fitted.
At 12v, and 12-12 scale it's 144W - which is quite unnecessary. Why the larger range when there are only half the amps floating about?
It would have been sensible, arguably, to use 12-12 at 6v and 8-8 at 12v . . . .
At the end of the day of course, it doesn't really matter what's fitted apart from on a concours machine. Regardless of what's 'correct' I personally think the best ammeters out there are the white-faced original Miller sort with the 2 inch face, one of which I have fitted on my A. (Not an original headlamp shell, no vandalism involved!) Can read it from the saddle without specs, it's dead steady and spot-on accurate. My little LE Velocette is similarly equipped. Most of the Lucas ones on my other bikes are flickery to a greater or lesser degree and less accurate - and many of the replica ones are poorly made.