gonna be putting a 2nd hand diff in mine soon to replace mine with a tired LSD

are there any checks or service type things i can easily do to the diff whilst it's out to make sure i dont put in another duff one? even if its just taking the cover off and posting piccies on here for others to look at... lol

obv. i'd replace the diff oil whilst it's out...

also this diff is currently in another car... can i check it whilst it's on that car? maybe try a few launches to check it spins both wheels? thing is it's in an XR4x4 so its not really got the power to spin the wheels easily... lol