Check-out Piewagon's sugestion on your shifter shaft seal and if you have a plug-in on top of the flange where the locking torque converter plugs in, there is a seal on that connection (I need to replace mine now. Replaced every seal in tranny when I rebuilt it, but that one and guess where it is leaking?). You wouldn't think that seal would ever leak, but it will.
Truck Tinker
