questions bout full time 4x4

[ol yellow 72]

hey guy havent been on here in bout 2 years or so, used to use the 67-72 side alot, but anyways picked up a nice 82 4x4 silverado setting on 78 running gear today for a nice $700. thing runs and drives like a new truck but im a lil confused with the full time 4x4 exactly how does the gears works since mine has no shift pattern on the knob.
next question when i go to what i think to be low lock and take off it pops the t-case out of gear, im thinking adjustment issue? if so how do i adjust the case?
and lastly is it a good idea to convert the front hubs to manual lockouts so it can freewheel?
any adivse would be much welcomed for this is my first full time 4x4