When I got my truck it was titled as a 1966, but it's a 1965. I had to write a short reason why I thought the truck was a 1965 when I got the title transferred into my name, and if the folks at the DMV had no problem with my explanation, they would change the year. when my title came in the mail a bit latter, it was changed to 1965. Just check with your DMV to see what it would take to get it right before you transfer it to your name.
The reasons I used won't work for your truck, because the options my truck lacked were standard on 1966 trucks, like seat belts. Back up lights were an option in 1964, but standard in 1966, as were seat belts.
