If you do a little research, there are options for rebuilt differentials with various gearing options. They are pricey (as everything with this car) and done in Germany by former / current MB employees. The original post I made back in 2004 regarding BergWerks would ship the differential back to Germany for re-gearing. His shop went under because the amount of people in LA wanting to spend $3,000 to put different gears in MB's was limited.

If you search you'll find it and it will cost you $2,800 to $3,500