So after some research it does appear that at least the cab is a 1961 GMC per the S/N plate found on the drivers side kick panel. Apparently the aftermarket VIN plat on the A pillar is not 100% correct. Maybe I have a GMC cab and hood with a Chevrolet grill and tailgate (Tailgate says CHEVROLET across it).
http://6066gmcguy.com/VinNumber.html