Jazn,
For the starter, consider just exchanging it with a Bosch factory rebuilt, which you can get at nearly any foreign auto parts store, or from the dozens of parts vendors that supply the MB trade. If you want to save a few bucks, you can have it rebuilt at any auto electric shop. Just be careful and ask them to use Bosch parts. Unless you are way in the boondocks and away from any major metropolitan area you needn't venture to far for this task. I had mine rebuilt once with a 3rd party solenoid. It worked well on the bench and in testing, but installed in the car it wouldn't disengage! It was tested repeatedly like this before we had the off-brand solenoid replaced with a proper Bosch. What I saved in the original rebuild was eaten up with the second solenoid. I should have just exchanged it.
Can't help you with the steering box, but I suspect that too would be an exchange part.
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored