i have an new 9" rear bought from Detroit Speed and its very noisy when i drive on the highway with little loud on it. The rear have an 3.70 gears . Is it some one who can say whats wrong with the rear.
You may need to reset the lash on the gears or you could have some bearings gone bad or even a busted ring or pinion. I am very familiar with rear end noise I've gone through many of them on many vehicles.