727 tranny yoke leak?

[toupee]

I noticed a leak coming from the rear of the tranny on my car.  I thought that it must have been the rear seal that was leaking so I got another one.  After I got to looking at it closely tonight, though, the seal is dry - no leak there.  It seems as though the leak is coming from around where the yoke is pressed onto the output shaft.  I only get tranny fluid on my hand when I put my finger in the middle area of where the yoke connects to the driveshaft.  Has anyone else ever had a leak like this?  If so, what can I do to get it stopped?

[375instroke]

Are you saying it's leaking from the center?  There is a plug in there, like a freeze plug.  I've never changed one, so I don't know what is special about it, like if you can put a freeze plug in it's place.  If you try to seal it up, remember.  Cleanliness is key.

[John_Kunkel]

Some early sixties slip yokes had a hole in the soft plug that closes off the rear of the yoke. The purpose of this hole was to allow air to travel back and forth to prevent "air hammering", the yoke with a hole was used in conjunction with an output shaft seal.

If the shaft seal wears out or if the yoke is used with a shaft that has no seal, fluid will leak from the hole. The shaft on the right in the pic below shows the seal in place.