Replaced differential oil with Redline 75W90 synthetic GL-5 gear oil at 4737 miles.
Spearfish25's DYI was a huge help. Thanks Spearfish, Rep added!
Check out the junk the magnetic drain bolt was hanging onto
From what I understand the Diff sheds its excess material at a much faster rate early, as in the first 1-2k miles. It's nice to have it out of there, and fresh clean oil in its place (not to mention the benefit of high-end Redline fluids). I expect the next Diff fluid change will have much less of this junk to clean out.