Eric, suggestion; you or Gearhead friend remove rear driver side wheel[that is the one you think sqeaking is coming from, right?], and while grasping Rotor hat, try & move up & down to check play between Bearing and Axel Race. Should be minimal.
Also check back of tire/rim for signs of gear lube.
Once a Bearing wears enough, the Axel Seal usually fails also.