Hmm, so I'm probably looking at a new diff, I guess. No pics, unfortunately. I overstated the "shavings" a bit, it was more of a heavy glitter effect on the bottom of the pan, and they weren't attracted to the magnet, so I assumed they were aluminum from the case. Combined with the part of a pin, that's why I was thinking pinion shaft retainer. I'm relatively confident in the suspension components, and the axles seem ok; the vibration starts only after applying a very specific amount of power, and it's one of those that's there or it isn't, there's no varying degrees.
If it comes to replacing the entire diff, I may just baby it for now and replace the whole damn thing next summer, I should have access to a lift by then. I'm also thinking I need a new PCS and possibly a new input clutch piston, so I don't know if it's worth putting the money into this one without doing a complete rebuild, which I don't have time for at this point.
Thanks for your help.
