I did a transmission fluid fill on a 1990 Mercedes and the factory spec was Dexron-III Mercon, which has been superceded by Dexron-IV Mercon. This should work for yours.
Search Mercedes-Benz 400-Class Questions
Mercedes-Benz 400-Class Experts
Related Models For Sale
Used Mercedes-Benz C-Class"
675 Great Deals out of 21,749 listings starting at $1,500
Used Mercedes-Benz E-Class"
582 Great Deals out of 18,198 listings starting at $1,700
Used Mercedes-Benz S-Class"
219 Great Deals out of 7,617 listings starting at $2,599