Actually when I look up a part in reverse like this it lists all the bodies it fits on. I happened to pick the one I described but I just went back to look at it and none of the pictures of the 124 540 part showed the harness I described. It turned out to be on a e420 that has this wiring.
The 190 pictures of that harness don't show what they hook to.
Bosch Master, ASE Master, L1
33 years MB technician