Rear end ID

[Mindl3ss]

The truck I bought came with this extra rear end. I'm not familiar enough to ID, so hopefully someone out there knows by looking.

Here's what I have identified so far:
3.42 gears (based on GM 1235128 12 41 10 86) stamped on ring gear

Is this an 8.2 or 8.5 10 bolt? Is it a locker/limited slip/open? Is it worth using over what I can only assume is a stock rear end (has discs on it already)

Here are some pictures of the gears (click to enlarge)




And what are these pieces that were loose in the housing?


Thanks for any assistance.