I can't believe every 2k miles is correct. I imagine it required a change at 2k miles but thereafter I think it's at the regular service intervals (annual or perhaps every 10k miles), if it requires any attention at all.
If it's the factory fitted LSD, then it's an advised (complimentary) oil change after the first 2,000 miles. Nothing else as far as I'm aware, though another one at 50 - 60,00 wouldn't do it any harm.
Pretty sure MB recommends the fluid in the LSD is changed again after the running in change, about the same schedule as the transmission fluid ie about every 3 years or 25000 miles or thereabouts.