722.4 transmission: is there a plug on top?

[Rocambolesque]

I have a '92 190E 2.3 with a 722.4 trans. I put the car on jackstands this winter to do a bit of work on it. The car is sitting outside. Maybe a month ago, I noticed the car had a pretty bad leak from the transmission. There was a small leak before, but nothing major. Out of nowhere, without even running, the car started leaking major amounts of trans fluid.

I also noticed that there were icicles (of water, no fluid in them) forming under/around the transmission when the outside temps was around 0C, meaning that water flows there naturally when it hits the top of the car.

I remembered that when I got the car, I changed the transmission fluid and slightly overfilled it. Fluid started to leak from the top of the transmission. I thought that was kinda wierd, since that would mean the top of the transmission is "open" and debris could get in it at any time.

Now I'm thinking of the worse: with all the snow/water that got on the car this winter, could some water have leaked inside the transmission and pushed the oil out? That could be the cause of the leak? I found this picture of a 722.4, there seems to be a plug on top of it (black, close to the driveshaft output):



Maybe someone who know those transmissions could chime in? This is the first automatic car that I'm really working on. I'm not used to some of the things I'm seeing...