65 Barracuda - 904 Transmission Oil Leak

Where is the leak? You got a cable operated trans. There is a kickdown shaft on top, about 2 inches from that cable entry, pointing straight up. It takes a lipped seal, and they do go bad all the time. Bad thing is you need to pull the pan/valve body or trans to pop it out. Its what that lokar cable is attached to feeding from the rear.
The selector shaft seal CAN be changed with the trans in the car. I think KD made the tool I have for removal and installation.