S2KSpaYellow

I have repaired many noisy differetials on Mustangs. I know Mustangs are not S2000s so don't flame me, but the way differentials are set up are basically the same. I have found the most common cause of pinion failure is not enough preload on the bearings. After taking out the ring gear and carrier I could spin the pinion freely when there should be 12 in/lbs of preload. After replacing the bearings, races and crush sleeve I would torque the pinion nut unitl the 12 in/lbs of preload was achieved. I never had any problem reusing the same gears.

Ludedude

Differential cases are not airtight so for that reason there's no way to insure that gear oil won't make a huge mess when dealing with a diff out of the car. They have an air outlet at the top to allow for expansion in case of overheating/overfilling scenarios and fluid can leak from there. I'd never ship one full or assume that one I received was full either.

Lesson learned I guess.

On topic, I'd make sure a diff/rear end expert re-assembles those gears and gives them an OK. They might still be within spec and will be able to be adjusted properly for proper engagement and lash. I'd certainly have a lab examine them for cracks though, and certainly flush the LSD unit well to make sure an crud from the bearing is absert.