Yes its in the shop on level ground.

Fluid you're draining doesn't look like dirty/chocolate milk, does it?

My Mack rear was getting water in it every time I drove in the rain and then blew a wheel seal; I didn't know enough about rears to know and the Mack dealer had to fix this issue 4 times until they (finally!) figured out the forward rear needed to be re-sealed. I know your truck doesn't have Mack rears, but thought I would mention water intrusion but that still probably wouldn't account for the extra fluid.

You been fording rivers lately? Ice-road trucking on thin ice?

I can't say, but does the power divider have a separate reservoir for lube?

Filled to the plugs. I am starting to wonder if the previous owner had over filled them. Came out blackish and smelled like used gear oil. Was time for a change. Could only find the 2 drains on the diffs so am going to guess everything is on the same reservoir.