Answering a customer.
1992 500SEL
Engine: 119.970
Transmission: 722370 03 616680
The leaking connector is on the driver's side of the transmission, just above the pan, and the wire goes through the drive shaft tunnel into the cabin.
It is a sensor, and the ATF is seeping through the connector and weeping out at the wire connectors.
Picture attached of the offending connector.
Switch, transmission overload protector B1.
MB# 002 545 45 14
Fastlane: Switch, transmission overload protector B1.
http://catalog.peachparts.com/item.wws?sku=W0133-1603525
Seal ring
MB# 016 997 35 48
Fastlane: Seal ring
http://catalog.peachparts.com/item.wws?sku=W0133-1715476