Question: have a '02 Sequoia 2WD with a 105,000 that I bought new. Have always had a shop do the rear diff oil change but just did it myself for the first time. Found in the drain plug magnet a fairly small amount of micro metal particles (like the consistency of silver model airplane paint) plus one larger piece of metal about the size of a grain of sand. Vehicle drives fine, makes no unusual sounds. Is this fairly normal to find at regular oil changes or should I not be seeing any metal "sludge" at all?

What you've described is perfectly normal. Gears rubbing together will always generate powdered metal and if a gear tooth has a tiny flaw you'll get the little chips. How long has it been since it was changed last?

It's been about 50,000 since the last change. I know others here do it every 30,000 but I haven't seen the need considering what Toyota's recommendations are (generally inspect, more than change depending on driving conditions) and the fact that I don't do any heavy towing, just very occasionally with a 1,500 lb tent trailer. Wanted to do it myself this time though and get it changed over to Mobil 1.

In my opinion your rear differential sounds like it is in great shape. just keeping changing the fluid like you are supposed to and you should have no worries.

did you add any modifier friction to the fluid? or just plain synthetic 75-140? what brand are you using?