Ring and Pinions

[bobscuda67]

Why are some sets of gears noisey and some are quiet? Is it the steel there made of or the heat treating thats used?
I found a used set of 3:55 gears I was thinking of buying for my 8 1/4 I'm rebuilding and was wondering how to tell if there a quiet set, if it's even possible.

 

[dart64gt]

I have a set of 3.55 for a 8 1/4 that I took out and I thought it was the gears making the noise it was not the gears it was the posi. Sell you the gears for 60.00 plus shipping from 92316 if you want pictures I will post them.