Gear setup on 4wd GMC?

[GMC4wheels71]

Hi guys.
New to the forum and these trucks. I just got a 62 GMC 4wd and all of the info is rubbed off of the 4wd gear shift. It feels like there's a 4lo (all the way forward), neutral (middle) and 4hi (all the way to the seat). Is there not a 2Hi on these older trucks?

I might have the hi/lo mixed up. I was afraid of breaking something so I didn't drive it, just put it into and out of gear.

Unrelated (?) it seems it doesn't want to shift into gear when I have 4wd engaged. It has the three on the tree gear shift.

Oh, and hubs? They don't turn, but they have screws on the outside of them. Do I remove the screws and turn = not locked anymore? I know they're locked now because when it's not in gear but in 4wd it tries to take off.
I'd like to unlock them but they don't want to turn.

A quick rundown would be much appreciated. I know this is a buncha questions. I'm just excited to get started