I have a Mark IV with the dipper switch on the manette. It also has a foot switch on the far left that I would assiciate with a dipper switch in an American car. I understand that one headlight is supposed to dip. Is this foot switch some adaption for the American market?
Does it look like either of these Lucas models?
You are correct that for the UK market the left one dipped to the left by the bulb being mounted in a swivel mechanism, and the right one had no dipping mechanism, just went off, when the manette control was turned to DIP.
Of course this would not be desired and possibly not legal in the US market.
Very possibly the dealer or somebody rigged it up.
Mine has been in the US since about 1977 and nobody ever changed it. I reattached the swivel so the left one dips straight down.