I'm using 75W-140 Royal Purple in my diffs...switched from Mobil One the same weight last time I changed it.

TOD case uses ATF fluid...I'm using Valvoline synthetic.

TOD drain and fill is easy enough...just crawl under your VX from the passenger side. You'll see the TOD case and two plugs with hex indents. Top one is the fill and bottom one is the drain.

Make sure you can break them both free before removing either one completely. Nothing like getting the drain out and then finding out you can't get the fill one out...