As best as I know, more than likely most Mercedes models starting with the 107 and the 116 were equipped with Fire Extinguishers as a factory accessory. I don't think I have see them fitted to earlier models, but stand to be corrected on that one.
Not so long ago, I had a trimmer (not Parks) refurbish the front seats of GB (more of that in another thread), but he fitted the retaining bracket upside down. Can't beat specific experience. Regards. Styria