8-3/4 Noise After Rebuild..What's Normal??

That's not too bad a price "if" it included a good quality gearset along with "all" the rebuild parts. But in any case, I doubt it's properly set up. My Chinese no-name 3.73's are quiet except for a mild coast whine. My Yukon 3.91's are made in China, but quiet.

Noise bad. Quiet good. Pretty simple. I think you knew that.