The noise only happens when there is a lot of torque to the drive line, thats why I suspected early symptoms of 'u' joints starting to go. Mine is a 97, so it's got coils in back too.

I just took the diff cover off and find a lot of play....again in the spider gears. I also see one tooth that has a small chunk out on the tooth face. Small meaning 1/16 diameter or so, but lots of play.

About 50,000 miles ago I lost teeth on the spider gears causing a failure. I cleaned out the rear and replaced the spider gears and they were much tighter with almost no noticable play in the set, only the ring & pinion slop, which would be normal with 100,000 plus miles.

Still looking for the problem
Doug