8.25 for dummie (me)

I just ordered a new basic ring and pinion install kit (RAT-400K) from Summit but something just dawned on me.
I am getting a slight hum from the rearend once warmed up. And a slight vibration more like oscillating at highway speeds. I recently had the driveshaft shortened,straightened and balanced by a reputable shop up here. I grabbed the yoke and found some slop and tried to tighten the pinion nut. I was able to get maybe 3/4 of a turn before "bottoming out" and had less slop but still some.
I thought the crush sleeve was to blame but it kinda doesn't make sense. If the sleeve is crushed and I tightened the nut more wouldn't it put excessive preload on the bearings? Or am I missing something?
Anyone out there can direct me to an exploded view of the 8.25 (1973) ?

Thanks in advance,Mike