they probably do have ford part number. as a lot of the old black cabs were made up from a lot of ford parts. the later black cabs upto N reg had these mirrors fitted as standard. google for images. we used to use these mirrors in the late 90s when black cabs were in scrapyards and with nothing like forums, not everybody knew of them! the later squarer black cabs used even more parts from the ford bin, such as 2.5 di tranny engines, cortina mk5 headlights and escort cabby rear lights.