Change a 2wd to a 4wd

[Ron 586]

I am trying to get a friend some information. He has a 83 GMC 4wd that he spent quite a bit of money on and the frame got bent some time soon after. He also has a nice 85 Chevy with a utility bed on it. He has a gravel pit and a construction business so he has equipment scattered all over west Tn. If the 85 was a 4wd it would be able to get into remote areas a lot better. He wants to use the running gear out of the 83 in the 85. He wanted to know if the 85 would be drilled for mounting the 4wd suspension or if he would have to do all the measuring and drilling to make it work. Thank you for any help you can give as I am not up on 4wd stuff. I guess I will be around now as I bought an old parts Blazer from Huck and plan to try to build a truck cab, flatbed short truck. (kind of like Yukon Jacks truck) Yes I'm a little old to be trying to learn new tricks but just gotta try it. Thanks