I'm guessing you meant to put this in a different section... But on a Subaru they also have a front differential, which your 2wd C10 doesn't. Subaru's website explains the difference between a symmetrical system liked theirs and a typical truck system... Here's some diagrams:
Subaru's System:
"Normal" Truck System:
It'd be pretty hard to convert your C10 into an AWD drive like that... If you want to convert yours to a regular 4x4, there's a ton of advice in the 4x4 section of thise site.
Personally I would never think of taking on such a project like that, and if I wanted more traction would add a locker or posi to the rear instead.