Ok, I fixed my leak this evening (I hope). Turns out this leaky connector is not electrical - it's some kind of mechanical actuator. It's called a "Shift Cable Connector Seal" in the AllPartsExpress store. My car is a '97 E300.
Pretty simple to replace, but not much working room if you're on ramps since this part is at the rear most end of the transmission.
0. Remove the rear transmission cross member. Two 13mm bolts and four 15mm bolts. The transmission will sag down just slightly, 2 or 3 cm.
1. Disconnect the part we're about to replace by giving the white plastic piece that goes into it, a 1/8 turn counter clockwise. It should pop right out. Just let the cord dangle there.
2. Using a T30 torx bit, undo the one bolt holding the "shift cable connector seal" onto the transmission. It should now wiggle around a bit loosely but you won't be able to pull it out just yet.
3. Drain the transmission.
4. Remove the transmission pan (six T30 torx bolts)
5. Look inside and you'll see a small metal lever arm that the "shift cable connector seal" attaches to. The arm rides on a metal pin. We need to remove this arm. Using a flat screwdriver, pry gently against the inside end of the metal pin. You'll see it start to come out the side of the transmission housing. Use plyers and grip the end of the pin to pull it the rest of the way out.
6. Catch the small spring that rides on the pin before it falls on the ground and gets lost.
7. Catch the metal arm and disconnect it from the plastic arm of the part we're replacing. Now pull the old part out.
Installation is the reverse of removal. You'll probably need a drift punch and a small mallet to tap the metal pin back into place. Use clean lint-free cloths and wipe each piece you've removed until it's amazingly clean before you reinstall them.
Since you're in here, you might as well drain the torque converter and replace the filter and pan seal too. Follow the proper procedures for refilling your transmission.
Open a cold beer and enjoy a leak free (and freshly serviced) transmission.
