They can't take ♥♥♥♥ lol. Get a 5speed Getrag(its a dog leg style tranny ) out of a 190e 16v or the 5 speed from the 190e 2.6. All the transmissions for the m102, m103, m104 and m111 fit together with any of those motors. The Getrag is good for 500 ft lbs of torque till it starts to break up, the 2.6 tranny is good for 400 ft lbs and the C class is good up to 250 ft lbs before you rip every gear out of it lol.
I just noticed you live in Indiana. Whereabouts in Indiana because I'm here in Jeff.
EDIT: If your looking for automatic stuff you can mix and match transmissions to get basically a race transmission.
You'll need the 722.6 out of the 97 E320 since it is the only version of the 722.6 that fits the m104. Then you need to get your hands on a 722.6 from an SL600 or an SLR lol. You ultize the valve body, gears and bell housing from the 97 and, in a nut shell, you use the case, clutch retainers, clutch packs, and shift solenoids from the SL600 transmission. Consquently I have both .
Another option if you don't want to mess with electronic transmissions is to get the 722.3 four speed auto out of a 300E or pre-95 E320. There are several people who make racing grade parts for those transmissions as well.