I too set up gears and do use the recommended specs but....each set of gears that I got had break in procedure. This is from Richmond gear....
http://www.richmondgear.com/01instructions.html
Break In: A new ring and pinion installation, especially a high numeric ratio with new bearings, can cause an excessive heat buildup in the rear end and cause softening of the gear teeth and bearings if a break in is not performed.
Street vehicles should be driven at normal street driving speed for approximately 10 miles, then stop and let cool for 30 minutes. Do this 2 to 3 times. Towing vehicles need approximately 200-300 miles of normal street driving before being used for towing.
On circle track race cars make approximately 6 to 8 laps at slow speed, then let cool for 30 minutes. Make 6 to 8 more laps at slow speed, then 2 to 3 laps at full speed, the let cool again for 30 minutes.
Drag cars need only an initial run-in since they are driven short distances and heat is not normally a problem with proper lube and backlash allowance.
NOTE: If after the above break in is performed, overheating of the rear end is suspected, repeat the final portion of the break in procedures.
I've done a lot of gear set ups over the years and have followed this procedure. Also, if a gear set had a slight whine, it never went away. Even got a new truck once that had a slight whine but it wasn't loud enough to complain about. It went over 100k miles. The failure was the oldest daughter totaling it out....