Upgrading from 2 wheel to 4 wheel drive
 

I have a 1991 Chevy C2500 with a 454. It is an extended cab with an 8 ft bed. It is currently 2 wheel drive but I want to make her 4 wheel so that it will be better in the snow and be able to take her off-roading. From my understanding All i would need is a transfer case with the same gear ratio, another drive shaft and a front axle. is that correct? also what would I do about front suspension, would I have to use leaf spring suspension or something else? It currently has the independent from suspension (Control arms, coil spring and shocks).

i'm just a college student working on becoming a gear head! Loves cars/trucks and doing my own work. Any help anyone can give me would be greatly appreciated!