The 83 300SD has a 120mph speedo. Not mine, but that's another story.
Part of federalizing a car when it's brought into the US is replacing the km/h speedo with an mph speedo. That's another reason to question the stated mileage on a gray market car.
That car was not brought into the US by MB for general sale. I doubt MB had anything to do with its importation. But it's not that rare. There are a couple of Euro 500SELs on eBay at any given time.