741 case 3.91 gears wanted

QUOTE: "Save ur self the headache of another set of whining gears..."

Do you think installation of used gears will cause it to whine again? Is that because the old gearsets had worn into an out of adjustment pattern? Is this less of a problem with higher gears? I've installed two sets of used 3.23s and neither whined. Did I just get lucky or is the problem more prevalent in lower gearsets? I did once install a set of new 4.10s that I never could get the whine out of completely so I'm curious......