[redmt]

Buzz , on the pinion flange torque,,, Slip the yoke off and replace the seal. Then tighten the pinion nut down to around 150 and check for bearing resistance and end play. If it's still turns freely take it down another 50 to 200. If it still has the same perceived torque rotation on the pinion then you should be good. Best case is to drop out the carrier and set the pinion pre-load around 10 inch pounds or rotational torque with the start and stop of rotation being smooth with out any jerking.
Spicer makes some decent u-joints.