Indeed!
Being in the EPC I can say - they are in the parts lists, but missing from drawings, particularly for W113.
I have noticed, that A LOT of parts are missing from the drawings of the steering, particularly the late type. I was really puzzled when I worked on my steering column in 280SL and was looking for the bearings. I see now that also for the early style you have to go to W110, W111 to see the parts on the drawings, not only in parts lists.