Does this part belong in rear diff?

[rgunlock]

Several years ago, I had a rear end from a 76 K5 regeared with 4.10 and a Yukon duragrip posi unit by a drivetrain shop. Had plans at the time that didn't happen, but now I want to use it on my 78 K15.

While I was cleaning it up for paint, a small steel cylinder fell out of it. The cylinder is about 3/8 inch diameter and 5/8 inch length.

I'd hoped to swap rear ends out this weekend since I have an extra day, but I'm kind of stuck. There isn't anyplace obvious this cylinder fell from. The only exploded diagrams I've found for the diff indicate it "may" be a roller bearing but I think its kind of large for that and can't imagine how one would have fallen from a built, torqued down assembly. Can't get ahold of the shop today.

So, does this belong? Or am I lucky it fell out before it could frag my rear end?

Thanks, Rick