Ok....Im goin through my Buddies Avalanche after his big crash (another post entirely

) and I am workin on the diffs right now.
The front diff turns (fingers) Smoothly. The rear Diff feels NOTCHY (best way I can describe it), and the center Diff feels better than the Rear (seems TIGHTER) but not as smooth as the front..
This is the first time I will be diving into the Differentials and I have no experience with how they should FEEL.
Should they be Buttery Smooth and FREE (almost loose)?
Should they have some Clicky/Notchy aspect to them?
Or is there some middle ground?
Any advice or Tips would be welcome.......
Thanks in Advance.......