Steve,

I also have a W115 '76 300D (super car!!).

I am a bit confused (what do you mean by "seating the feed through rubber")...did you replace the speedo cable itself (feed the square- shaped metal cable through the housing ) or did you feed the housing/cable combination through some other piece of rubber?...the moderator (Stevebfl) suggests that the cable and housing are inseparable.

Any installation details that you can remember would be greatly appreciated...I've replaced speedometers on older American cars but this looks a bit different...am I overreacting?

Robert