2wd is what I used. I have no idea about the 4wd, but you could check it out on the GM Heritage pages. You are familiar with those, yes?

https://www.gmheritagecenter.com/do...hevrolet-Trucks/1969-Chevrolet-Truck.pdf

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end