wonderin about a noise in my rear end?

[mado13]

I have a '95 f250 on a 1 ton chasis and drive train with a dana 60 front end.  Im tryin to sell it so i was replacing fluids and checkin all the little noises and what not so i could sell a mechaniclly sound truck.  
Heres my problem, when at a crawl(in gear, not giving any gas) and with the steering wheel slightly turned either way there is a kluncking noise that comes from the rear end.  I havent opened up the diff yet but when i checked the plug there was no metal.  I was wonderin if anyone had any suggestions before i open it up this weekend?  By the way, the truck is for sale/trade for a yota...
Thanks for your time, Marty

[DTB]

sound in the rear-end? like this?   haha sorry i had to ........

is it locked up? or open?

[mado13]

i believe that its open, it may have a posi, not sure though?
Any ideas?

[Hottrod81]

If it's a limited slip, it could be the clutch packs are worn.

[79coyotefrg]

im leaning towards a blown u joint in the front knuckle

[mado13]

thanks, that helps alot, im goin tear into it this weekend and ill let yall know!
Thanks Again Marty