Yes, what you will be looking for is the line that goes from the engine down to the transmission. Often these hard platic lines get cracked or disconnected. This line connects to the vacuum modulator via a simple rubber tube. These also get hard, brittle look good but actually leak.
My guess from your description is the trans will probably work pretty well if you get out ALL the ATF, thus the suggestion for the torque converter. DEFINITLEY replace the trans filter with ONLY a MBZ filter.
Let us know how it goes. I hope you scored and you fall in love with your car. I'm rooting for you.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)