This just happened to me, same problem, I have the parts and ironically mine is being finished tomorrow afternoon. Fix both sides, I went to fix one and then the other side broke and had to do the whole thing over again. Have a good mechanic do the job, if you're not going to do it, theres lots of tiny little peices to work with and they're a complete and utter pain in the ass.
It is a do-able DIY, but find someone to help you. It's tough to go back and forth from the driver side to the passenger side and try and line everything up. Also, make sure you have all the parts you need, I went in for one side and found I needed other stuff and ordering them from my local MB stealership's parts department cost time.

Best of Luck.
Feel free to PM with any quesitons, as I searched and found no help whatsoever. Not saying i'll be a big help, but I'll try.

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-Sam
93 300D
210k - Sold, but not forgotten.