I made the huge mistake of buying a rebuilt steering gear for my SL from mercedessteering.com. The unit they sent cost me $325 plus shipping and guess what. It was a "Spray and Pray" rebuild. This is a rebuild that consists of only a paint job, nothing else. To make a long expensive story short, I rebuilt the box myself with the help of David Petryk's fine help, see
http://www.davidpetryk.net/Mercedes/Steering.htm and got the job done. The nice folks at mercedessteering.com told me that they would give me another "Rebuilt" steering gear if I sent them the one I waited two weeks to get from them. They also said that it was not their policy to refund customers for "Rebuilt" merchandise. What a bunch of A Holes. Under no circumstance do you want to do business with these people.
The rebuild is no big deal. I did mine in about 2 hours. The steering on my 87 560SL is now perfect.