Go to http://www.mbusa.com, click on "Mercedes In-Depth" then "Classic." Then at the top, click on "Classic Center" and "Technical Literature" to find the part number. Unfortunately the page is down now, so you will have to try later.

Once you find the part number, call 1-800-FOR-MERC (the same as roadside assistance) to order the CDs/DVDs. You will find them surprisingly affordable.