I bought a rear from someone once that had 4.56s in it (8 3/4) and it had the most horrible howl ever. Same thing, edges of the ring gear teeth were rounding off. This tells you your pattern is WAAAAAY off. If you run gears for any length of time with the pattern not set up right, you are never going to get the gears to set up and run quiet again. There is no way you are going to get gears grinding on the edges of each other quiet again. New gears time.