Transfer Case & Diff oils... what's the best stuff?

[Lugnutt]

I've got a 72 K10 4x4 auto with a posi rear diff and about 95,000 miles. I've got the pre-interaxle transaxle transfer case; by which I mean it's all gears (see pic). and I've also got the posi rear end (see pics). I want to change out all the fluids with the very best oils I can including the front differential (sorry, no pic). Can any of you recommend the best oils for these parts? Also, based on the pictures, what is the proper description or name for these two components.

Thanks for the education, I'm humbled by the knowledge you guys possess.