Maytag, since the rack is full of gunk I am guessing the oil rings to be the culprit
If your car is drivable clean everything up, :-) and you should be able to see where the leak is originating.
Not sure I understood you well (sorry), are you suspecting that the leak is coming from the rear side of the fitting, at the end of the rubber hose..? That is sipping alright but not enough to create the mess at the rack anyway (IMHO).
But once you wash it, we'll see for sure
