I've had this noise driving me nuts since I bought this truck last fall. I only hear it when I am first accelerating either in drive or reverse, then it goes away. Sounds like bolts in a coffee can shaking around. Anyway I think I tracked it down to my rear diff and I figured I might as well change out the gear oil in there and poke around. I didn't find any obvious damage, but then this is the first time I've the cover off a rear end so who knows. I did find lots of metal dust and flakes on the magnet along with these 3 little beauties. The .308 round is in the pic for size comparison.

I'm still letting the rtv set up so I haven't filled it or driven it yet to see if the noise is gone. Anyone have a clue what these little pieces used to be?

 

looks like shims or parts of a factory LSD assy... they are notorious for exploding and leaving chunks... mine had similiar peices when I had it rebuilt... I think they were pieces of the lsd clutches..
If you do have the factory lsd you should address it the right way and repair or remove it or it will cause some expensive damage and likely leave you on the side of the road......it took out the pinion bearings in mine.. I caught it early..

 

Just had the same problems. Had my diff fluid changed and immediately started hearing noises with a shudder when making tight turns. Pulled the cover found broken retainer clips and small flat pieces metal. They were from the the clutch packs on limited slip rear differental. Luckily none of the metal chunks had'nt damaged any gears. New clutch pack kits and good as new, again. There is very detailed DIY post with pics in here,search. Took mine to a shop.

 

Thanks for the info. I am done spending money on this rust bucket. Between the 4 bucks a gallon for gas, the front u-joint I need replaced, the 4wd not working again and now this differential crap I am done. I have been too afraid to check to see if the plenum leaks because I don't want to know, but I think it does. I love the truck but I can't afford to keep dumping $$ and time into it anymore. Bummer too because I just had to rebuilt the tranny at xmas. My *** is still stinging from that bill.