Regarding the ammeter, the headlamp I have fitted is a new-old-stock item retrieved from a dealer in Wales. I know it is correct because it had the correct headlamp switch and the internal wiring, under the switch panel, was obviously original. Also, of course, the plug/socket arrangement looks original so I have assumed the ammeter is correct. The unit was supplied in the original Lucas box, somewhat dusty. I daren't say how much paid for it!!!