I bought a new 260E back in 1989/90 and the radio was an extra. When doing the deal with MB Bristol, we agreed they would fit a radio for me and electric aerial. The radio fitted was a Blaupunkt but the exact model escapes me.
I will check later on, but i do have the hand book that came with my 260e with the name on it and i am sure its a Blaupunkt, but the model i am not sure The radio is atill at my cousins .as he purchased the car from new .But pulled it out and fitted a cd player
fromematt the radio type is a Blaupunkt Cassablanca SQR 49 or Coburg SQR 49 The wiring diagram is sitting in the wallet also .Thats 100 % positive it was the right fit for your car from new ...I have a Savilla fitted but a cd player.and not original .