opened the diff

I pulled the diff out of the car today, and of course im going to drain the differential fluid because im going to be getting it welded.  So I unscrew the drain plug to drain the oil and all I get is a hiss of compressed air that comes out.  Eventually oil started to come out.  This means the oil had not been changed in a really long time.  

The magnetic drain plug had a bunch of sludge on it and stuck to it were some chunks/shards of metal.  

so i took off the cover on the diff to find that...

the shards of metal came from the spider gears, specifically the ones on the top and on the bottom.

I would replace them, but I wont be using them anymore because the diff is going to be welded.