On these cars as well as the w124's the leaking area you point out usually comes from a leaking front tranmission seal. As the car sits, the tourque converter applies alot of weight to the bottom of the seal deforming it, and it leaks. Check the archives for how to replace and any other things needed. One thing for sure is the tranny has to come out to do the fix, it's a big job.

I have the same leak in my wagon, but I lose only about a cup of fluid every 10k miles, so I live with it, sucks that it leaks, I hate leaks very much, but looking at 12 hours or so to pull the tranny fix the seal, and reinstall is just not worth it. When the trans comes out I will do more to it like shift kit, higher stall converter etc, meaning more hours more money. On mine, my leaking fuid was mixing with drifting engine oil spray on the trans cover, so by the time it droped to the floor it was a reddish black.

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)