front diff noises.

for starters i did try the search function, so dont flame me too bad...anyway i have a 98 xj sport with 8.25 rear and d30 up front. anyway I was backing out of my muddy yard the other day (in 4wd), and when i got my DS front wheel onto pavement the PS wheel started spinning and with the spin came a terrible grinding coming from the front diff (my best guess). I took it out of 4wd and finished backing out, everything was fine. i drove it on pavement with 2wd and 4wd, everything was normal. i havent tried spinning the front PS wheel again...What do you guys think...what would you do? wait for the noise again? what should i check? thanks in advance.
matt

anyone at all? TTT!

Shoot it. That's what I plan on doing. My front end makes all sorts of odd noises too.