Venting a little - Differential Question

[Zilverado]

Okay, I apologize again for a non question, but the people on my Nissan Forum are about as useful as a snowmobile in Iraq...

I thought this might be a generic question for all you "pumpkin" experts.

Can anyone tell me what amount of lash (if that's the correct term) I should have in the pinion on the rear end of my wife's '92 Pathfinder. It's a non-limited slip diff.

We get an annoying "clunck" from the rear sometimes when engaging the accelerator after slowing down (especially at "rolling" stops).

The u-joints are tight, but the pinion seems to have a fair amount of rotational play in it. Is this normal?

Any advice.
Thanks

P.S. I (and my wife) really appreciate it. Once I get some of these things fixed, she'll let me get back to my Chevy.