Throttle switch. I think it is for the early throttle - when you hold it in such a way the its base is facing you, you can turn the pivot right, as on the picture. I think PN is A 0005453404. Fits engines:
M127982 and M127984 - so fits cars W111 014 (220SEb),
M100981, M100982 and M100983 - so it fits all W100 cars and W109 018 (300SEL 6.3)
It comes from a throttle of a car with manual gear box - points are like new, it has never seen any electricity.
$250 plus shipping.