2006 WRX 5 speed with pieces inside

Hi Guys,
First post for the new to me WRX. It has 135K on it and I've been driving it for 2 months with no issues at all. Until a couple weeks ago on the way to work I felt and heard a clunk going into 4th gear and then 5th gear accompanied with a minor whining noise in those two gears only. Got the car back home and got under it to see if I could tell if it was rear or center diff. The sound seemed like it was coming from the rear so I took it out and looked but found no evidence of a problem. Clean gear oil too. So... I pulled the rear trans case and center diff out. It looked overheated and generally not good. I found 1 piece of what appeared to be part of a gear (smaller than a dime). I took the diff apart as far as I could but did not see where this piece of metal came from. Next I pulled the center case and found a bunch more pieces of what appears to be three different parts. see photos attached. I ran a magnet into the bottom of the fwd main case and come up clean. No debris at all! Is there any chance this stuff came from the center diff and I'm not getting it apart far enough? I really don't want to pull this tranny and split the case if I don't have to. One of the piece selections is thin stamped metal, the next selection is thicker and cast, and the 3rd appears to be a gear tooth but the machined radius I see is in line with the piece kinda like a pinion gear almost but the pinion looks good through a scope and it is way thicker than these pieces. I think I got the pics to work. If anyone can help me to know where this stuff may have come from it would be great. I have a new center diff and new rear transfer shaft and output shaft because they had a couple teeth that had small bites out of them but the missing material from these is not what I have in the bottom of the middle case. The third picture shows the pieces on their side against a pick.

No comments? Lots of lookers. What I'm hoping is this stuff came from the center diff. If anyone knows what the diff looks like completely apart, a picture would be great. A good diagram maybe. I got all the disks and spider gears out but that's it.

i would not chance it without taking it completly apart. you may have chunks or filing in the hubs or some of the bearings. to me it sounds like its time to rebuild or replace it to make it last

So as long as I know I may be buying a used trans from a wreck, why not try flushing the trans and give it shot? This is my work driver and I have a backup.

Well I've been driving this baby for the last 3 months, 80 miles a day. I think it's safe to say the chunks I found were from the center diff because I replaced it and it sounds good again, no clunking or grinding as it did before tearing into it.

Well 11000 miles later it started whining on the day I had drive to work and back about 80 miles on ice. The whining only comes on at about 50 mph. I also have an occasional clunk going into 5th gear that also started at the same time. Not sure if the ice was a coincidence or not. Plan to drive it till it gets warmer and buy a used trans and rear diff from ebay

After replacing the center diff from the first instance and getting whine back after a while, I found that when I was looking at the rear diff initially, I didn't get the shafts popped back in all the way! Neither of them were snapped in. They would and did work great on dry road but when I got onto some ice, they would slip and also make the clunk noise in 4th or 5th gear. I didn't believe some of the posts I read that said to check the axle shafts until I saw this for myself. Just took a mallet and popped them in about 3/8ths inch and all is good. Not sure how many miles later now but a butt ton as this is my daily driver and I do 80 miles a day.