If it were me.....
Call them cussing and screaming, sound like someone important. If you get no results, demand to speak to that person's manager. Be sure to have a second "mechanic" handy (doesn't really have to be a mechanic ) to tell them how bad the noise is. Sometimes you gotta do what you gotta do. Hope this helps

JR

 

same prob here. My 3.73's wasnt that bad as far as whine. I sent it back to Moser to have 4.10's installed bout yr. later and when i got it back it whines SEVERLY!!!. I'm sick of calling them and complaing, I've got close to 3k in this damn thing and u think it would be somewhat better than what it is. And adding 2 bottles of additive does help, GM additive is what I used. I change my fluid bout every 3-4 oil changes, seems to help but it is VERY loud. Seems to hold up good I guess.
wish I had went with the 9 inch though, too late now.

 

Moser agreed to send me new gears, setup kit and reinburse me the 150 bucks for the gear setup after a scathing email I sent them. Now I can get someone competent and that cares to install my gears right!

 

Sounds like the thing to do is just order the rear end bare w/axles, and build it up yourself (if you know what your doing) or a reputable shop. That way you know it is going to be right.

About the ford 9", I love that rear, but it deletes the anti lock brakes on 3 channel abs, no good.