There are changes every few years, so it won't bolt right up.
60-62 had torsion bar suspension up front
63-66 coil spring front end, core support brackets different
67 almost same as 66 except core support brackets
68-72 all same
That's for 1/2 tons, I don't know beyond that. This is off the top of my head, there are more changes I think between 66, 67, and 68.
Hope that helps.
