FWIW, I had a leaking transmission on my E420 that I thought might have been the pan. When I got under to take a look, there was fluid coming out the aft right side where the kickdown solenoid valve is located. There is a plug there that was loose, so I pushed it in, not knowing if that was the problem. The leak went away immediately.

I bought the reseal kit and have it sitting here on my desk but figured that if it's not leaking right now I will leave it alone. This leak had been going on for several years and I had been adding about 1 quart of transmission fluid every 1,000 miles. I guess that's one way to keep the transmission fluid new. Anyway, you may want to check this area for leaks. By the way, the leak didn't start until I pulled the pan to change the oil. I may have bumped the connector on the re-installation of the pan.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles