[blue sky]

Nick, Those were US sourced lamps (sorry don't know the source). AC supplied the Mk3 with a WL13 lamp for the ignition, same style as the turn and high beam lamp but with a special bulb holder. Lucas also idenitifies the lamp in their supply list for the Mk3 to AC. Some cars had them back then but most probably didn't. Experts will know more about number specifics. Shelby's group probably changed them out for reasons Roger spoke of, if the bulb holder comes out there is a short possiblilty.
AJ