4x4 frame interchangeability between 67-72 & 73 up

[coggonobrien]

Hello I am getting geared up to build a Chevy 4x4 and had a question
pertaining to chassis interchangeability. I have been offered a dirt
cheap 1975 4x4 manual to be used in my 1969 truck project. basically
i can get the 2wd 69 for cheap as well but ideally want to build a 4x4
to be used as a farm truck. I know the crossmembers will all be in
the wrong places but I am under the impression that the 69 box will
bolt directly to the 75 frame. then all the cab mounts, radiator core
supports, bumper mounts, etc will have to be custom mounted. Is there
any truth to this and has anyone done it? thanks, Dave