I've been tempted to do this to my 79 C10,using my 74 K20 as a donor--but its a hellatious job--you have to remove the entire 2wd front suspension/engine crossmember,install the leaf spring hangers(front)and bushing/shackles,the rear spring shackles and hangers must be swapped for 4x4 ones,the cab might hit the transfer case without a body lift,you will have to drill a lot of holes(the frames arent usually drilled for both 4x4 and 2wd),you need all the 4x4 drivetrain,tranny ,transfer case,shafts,crossmembers,and thats just the bigger issues,there will be lots of little details involved too.Its easier to put an ad in the classifieds and sell the 2wd truck,and buy a 4x4 in the long run,unless you are a glutton for punishment(like me! /forums/images/graemlins/1zhelp.gif)