Drivetrain Clunck Part II

[TBone]

1994 LT1 6 speed coupe. Here is what's gone on so far. I was able to reproduce a clunk in my driveway on a slight incline in a slight turn. This I figured was a positraction clunk. I bought a kit to put a drain plug in the differential and changed the oil in the unit. I added a bottle of GM posi additive and filled it up. I went to the church parking lot and did figure eights. The clunk that I could reproduce in the driveway is gone. I still had a clunk when taking off from a stop, intermittently. I jacked the rear up and to my surprise both rear wheels were loose when checking for bearing play. I replaced both rear hub units and the noise/clunk is gone. The rear area is quiet and I think I've alleviated some vibration. It seems smoother at 65++. Now.... I have a slight clunking that sounds like it's coming from the rear of the transmission. It happens when I let off the gas and add power again. What do you think this could be? A worn yoke on the driveshaft? I think if I can solve this one it will be clunkless.
Thanks