A couple weeks ago I finally got a transmission shop to fix a minor leak at the shifter seal on my 350 turbo. I brought it home and no leaks for 3 days. I then went out of town for two days and came back to a puddle under the yoke at the rear of the tranny. I was able to see the fluid dripping from the yoke. The car was not driven at all between bringing the car back from the shop and when I noticed the leak. I had never had any leak problems from this area in the past.

I took the car back to the shop the next day and they put it up on the lift and were never able to find a leak. I even went to the shop when it was up on the lift and pointed out exactly where the leak was coming from and it was bone dry.

I brought the car home and it was fine again for about 3 to 4 days. It then started to leak again from the yoke at a pretty good pace.

I drove it a little last weekend and noticed the leak stopped again until Thursday when it started back up again.

Does this have something to do with the pressure build up after driving? Has anyone else had this problem and what was the cure?

Is it the original yoke? If not, it may be one from one of the Chevy trucks that has a tiny hole in the center of the yoke that was put there as an air vent, with an internal seal that kept ATF out of the spline area. My Suburban has one, & it leaks if you park it at the wrong angle. It leaks down the back side of the yoke, in front of the U-joint itself.

Not sure if it is orignial or not.

Any idea how big a job to repair the internal seal or o-ring?

The internal O-ring is leaking. Have a good time finding one to replace it.

Since the case has a vent, pass side above the dipstick, I removed the yoke, degreased it, wiped it clean with lacquer thinner, and filled the void, external dish created by GM, with 3M Liquid Steel. No more leak after curing.

As for the leaking several days later, this is attributed to the fluid level in the case rising as the fluid from the torque convertor is draining/leaking back through the oil pump and filter. The fluid id seeking its lowest level. The case vent, or rear yoke, depending upon angle parked, is allowing the new fluid level to leak out.

Nothing to worry about, natural cause, no parts have failed.