vryterry. I dealt with the same problem on my ´04 ML500 and was a pain in the neck to get the part. Check on the web and you will find the rack and pinion ranging from $250 up to $500 Dollars, the problem there is that most of the dealers don't have it in stock, however, some of them will offer that you remove your rack and pinion and ship it to them for rebuilt. If you want and can afford it go to the MB dealer. There you will get a brand new part but you may end up paying over $1500 Dollars for it.
I would suggest: Go for the parts supplier on the web. Make sure you provide your VIN for proper part number fitment. Once you get your part, open the box and make sure the part you are getting is IDENTICAL to the one you remove (or will remove) -there are more than one part numbers for this SUV and it happened to me that I got the wrong one which caused a 3 week delay on the repair. MOST Important: If you will do-it-yourself, let me know so I can give you all details for removing and replacing the part. Let me tell you that is tough - but fun and rewarding to do it. Let me know if you need further directions. Good luck!!.