Gears whine, bearings roar.
A mismatch of the pinion to ring gear is what causes whine.
Could be a loose pinion like RRR says, or it could be a pinion depth issue.
The best way to find out is to use the pinion depth tool to get it right.
THEN set the backlash.
The tool tells you exactly where the pinion should be, and that number is usually stamped into the end of the pinion gear.
