Frames 60-62 then 63-66
60-62 are an X-Frame. 63-66 are ladder frame.
Good thread with pics:
http://67-72chevytrucks.com/vboard/s...d.php?t=325736
Cabs 60-63 then 64-66
60-63 cabs are wrap-around windshields (knee knocker cabs).
Hoods 60-61 then 62-66? Guessing on this one.