Changed the oil and the transfer case fluid. Will finish the transmission, and front and rear diffs next weekend since I had to order the oil. Going with all Amsoil except the engine, and it gets Pennzoil Ultra Synthetic.
The TC fluid (ATF) was not too bad and didn't smell burned or anything, but the fluid was fairly dark and there was quite a bit of "gunk" on the magnetic plug. No shavings or anything which would indicate undue wear. I did notice that it shifted a lot quicker after the fluid was changed though. The 4wd light used to blink for several seconds after you turned the switch, and sometimes it would take 15 or 20 seconds to go into 4 low, but it shifts almost immediately now. I will see how it works after I run it a while. Hopefully it will help to milk a few more miles out of the truck in the long run, since I put quite a few on every year and I want it to last.