100k miles on my shop truck and a weird surprise in the diff fluid

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Pulled the drain plug on my old F-150 at 120k and found the same kind of glittery mess. Turns out the pinion bearing was going bad, but I caught it early. Flushed it out with some cheap gear oil first, ran it for a week, then dropped in the good stuff. Been 30k miles since and no noise or metal on the next change. Worth checking your driveshaft u-joints too, that slop can work its way back and mess with the diff.