I had another look under the car yesterday evening and the drag link is about one to two cm higher on the relay arm side side. I also noted that the length of the relay arm is about 1 cm shorter than the pitman arm. I had noted that on the workshop manual and I though it was a typo, especially as they are reported to be the same length on the w109 6.3 (but longer on both side). I found out that the end of the arms is equal relative to the front subframe. But the pivot axis of the relay arm is about 1 cm forward compared to the one of the steering box. I wonder why that is and why it isn't so on the 6.3 too.