Dexron III for pretty much any of the 3-speed and 4-speed ATs. Sometime in the late 90s MB went to 5-speed ATs that take another kind of fluid. These cars don't come from the factory with a transmission dipstick so there's no easy way to check or fill the AT without buying additional parts.

There are synthetic blends of Dexron III in the Mobil 1 and Redline brands and probably others.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD