They are a Mercedes Dealer in Gainsville, Florida. First link is to there MB site and second is site to order parts. I deal with Tim, call and ask for him. I suspect the transmission is new or remanufactured by Mercedes or whoever they have to that. If I have to replace I think I'd be inclined to go with a MB factory new or rebuilt.

http://www.kraft.mercedescenter.com/mbcenter/b/index.jhtml;jsessionid=CFBH5GYJV4QUMNKDDOFSM4RVIMNYUJVC?null&_requestid=274960
http://www.trademotion.com/partlocator/index.cfm?siteid=213951&catalogid=0