Could be anything. As above completely remove the rear driveshaft and see if the problem is still there. Swapping another part in place and going for a test drive isn't going to eliminate the rear end as a source. That's going to run you around in circles and you'll still need to troubleshoot. Until you've eliminated 1 potential as a problem you don't know whether or not to move forward.
Odds are im typing on a tablet. It takes too much effort to add some punctuation. Im lazy, get over it
Never underestimate the power of stupid.