Lou
Basically What Scott said
60 thru66 had the same body style Fleet or step sheetmetalwise 1/2 ton to 1ton CAB Wise
With the ton and a halfs and bigger the fenders were bigger
Major difference CAB sheetmetalwise is between 63 and64
60 thru 63 has a wraparound windshield called"panoramic" by GM and consequently the doors are totally different.
64 thru 66 have a so called "flat" windshield and GOD knows I Blessed Him Countless times After NOT sliding out and Smacking my Knee on that DAMNED Dogleg.
And YES YOU Can use a 6000 series cab on a C10 only thing is use the correct trans/floor cover.
Hope this is not too confusing
Regards