Feels like bad U Joints but not

Just in case anyone wants to know, pulled diff out this weekend and everything looked fine and turned smooth. Was no preload on pinion so I tightened it up a little and then you could feel it binding up. Tore apart and whoever rebuilt this a while ago never cleaned the crap out of the crush sleeve and bearings were running in what looks like clutch dust from the Sure Grip. Fluid that drained out looked fine and carrier bearings were unhurt