Yes, they can. I'm removing the wires from the 6 pin socket which was in the car to the 4 pin socket I got from the junker and the lights are working. Switching the pins is easy. I'm keeping the six pin socket in case I ever decide to revert to Euro lights.
But I wanted to make sure that people knew that the 4 pin sockets used on US 126 models are not all the same.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13