How does the diff feel when it's not in the vehicle? if it's good, then it's something on the vehicle, if it's bad then it's something in the diff. Did you check the diff pinion?
Is the noise there when the truck is rolling, or just when tires are spinning opposite directions?
I would check for any debris in the case, and for any screws sticking into the case.
And I would double check the post numbers for the pinion and ring gear to make sure they are both the spiral cut gears
Doesn't seem to begin swapped front to rear the ring gear and housing and it stopped making noise so I'm not to sure as to what changed