The 4-5-6 Chevy truck cabs are interchangeable and there are no distinguishing features between the three years, with the exception of the VIN. With the front sheet metal off the truck, thus no body badges, to identify with, it is virtually impossible to distinguish between them.
I am not sure what you are referencing, but the three years are interchangeable on your '66 C20 frame. I would be glad to chat with you about the process, if you want, feel free to give me a call anytime. I like talking '60-'66 Chevy/GMC trucks.
In short, you do not need to find another cab...the '64 is a perfect donor for your '66 C20 frame.
Edited to include: The '64 cab had the bolt-on inner fender bracket, that was a carry-over from the earlier '60-'63 cabs, unlike the '65 & '66 cab inner fender tabs, that were part of the firewall stiffener.
Last edited by 4-5-6 Chevy Trucks; 02/16/2010 4:54 PM.
