Rearend noise what is USUALLY the cause

[AKcharger]

Is it bearings or worn Ring & Pinion? ( I know it could be all but just looking for the most common cause

[RD]

your backlash could not be set properly causing your gears to whine.  what exact sound is it:

whine

metal on metal grind

light scrape as the wheel turns?

[AKcharger]

A whineing noise in wife's '72. I was going to change out the chunk but want to know if the ring and pinion are still good or likely worn

[RD]

was the case a rebuild or stock?

if it was rebuild then the gears are probably breaking themselves in, but it shouldnt whine like really loud.  if it is stock then the backlash needs adjusting.

[John_Kunkel]

Is the whining noise audible when accelerating? Decelerating? Steady whine? Only in one speed range?