I have a 1999 Mazda b4000 it has 160000 miles on it do to the previous owner running the differential out of oil I replaced the carrier, pinion, wheel bearing/races and rear driveshaft u joints. I have a loud whining noise that's coming from the rear. What could it possibly be. Thanks

 

How was the gear pattern when you put it back together? Set the preload correctly? If the same ring and pinion where used the noise could be in the gears.

 

is the noise all the time or just on deceleration. Mine has a little noise on decal, but I can hardly hear it anymore

 

Its all the time. I set the preload to about 16 lbs of torque. I'm beginning to think it's the gears? But they looked decent to the eye.
Could a worn axle shaft make a whine almost sounds like a bad wheel bearing but they are brand new.

 

What did you set the backlash at and did you check gears pattern with white grease

 

I used the same exact shims that were on the pinion. I did not adjust the backlash

 

There is your problem. If you havent ruined anything yet you need to get back in there and set your backlash and check your gear pattern. Gears arent just something you can throw together.