'60-'63 are the same and '64-'66 are the same, as you know, but I am not sure why they are listed as the same in the catalogs. I recommend buying from the supplier that sells the set for '60-'63 and '64-'66, so you know you are getting the correct door/cab seals.
Try:
www.truckandcarshop.com
www.bowtiebits.com
www.classicparts.com
www.gspp.com
Good luck with your project.