2x4 and 4x4 frame ?

[jcueckert13]

I have a 1970 GMC c10 lwb stepside that is 2wd and at this point it is sitting in the front yard with no motor and is used for parts storage, i also have the frame to a 1971 4x4 suburban sitting 20 miles away with the front axel, springs, mounts and steering linkage that due to mud i cant go look at right now. what i am wondering is what diference is there between front half of the frames? I am wanting turn the gmc into a 4x4 and looking at the front end all of the 2wd parts just bolt on so i am guessing it would be possible to just bolt on the 4x4 parts and with a new trans be able to have a 4x4 truck.