I have over one inch of rotational play in the driveshaft of my 1997 Subaru Legacy GT (215k miles). Link to video of actual vehicle and symptom below.
Vehicle makes clicking sound when NOT under load (accel & braking). Lots of regular clicking that increases in frequency with speed while coasting. R&R'd front axles, rear's look good. Driveshaft has zero fore/aft play but over 1 inch rotational play. U-joints feel solid and are not the source of play. Sound seems to be coming from inside rear differential. Checking/changing diff oils now, although I feel this is some larger mechanical issue. Thoughts? Thanks in advance