Very similar here in Washington as well. My Uncle has a 77 F-350 crew cab that he built out of at least three different trucks back in the early 90's.
The 4X4 Chassis came from the truck he had bought new (as a standard cab) in 1974ish and then he purchased a 2wd crew cab cab and chassis from a wrecking yard and married the two together. Those two chassis plus a bunch of other parts made the truck he has now, which was inspected by the state patrol upon completion and given a title and registration.
I may be mistaken, but I think that what Ruckin69 may be looking for is which specific frames, from which specif years will fit under his truck.