rear end noise and vibration

You don't say what type of noise. Roaring is usually low fluid. Humming/vibration is often a u-joint (in addition to the driveshaft, there are four of those in the half shafts, remember). Could be the splines in half-shafts, or more likely the boots have torn and allowed dirt to get in there. Half shafts are relatively easy to get apart, clean up and put new boots on — although its a pain to get them out. But by the time you order new clips and dust cover and clamps and wait for it all to arrive, it would probably be quicker (and cheaper) just to get a good one at a junkyard and put it in. Sharp raps or clunks are worn mustache and/or differential bushings and/or a worn/stretched strap (that goes over the nose of the diff to keep it from coming up and hitting the floor). It could also be the diff just wearing out, although these diffs are so bulletproof that they're usually about the last thing on the car to go. If it were me, I'd double check for low fluid — maybe just change it out for new anyway — torn/holed dust covers on the half shafts, and worn half-shaft universals. Sounds like you've done about everythign else.