We do not have the 1964, '65 or '66 Dodge TSBs on HH yet but here is a link to the 1966 Plymouth page -
https://www.hamtramck-historical.com/images/TSBs/1966/66-1_page2.jpg
As you can see, the Hamtramck A bodies for '66 started at 500001.
They were also built in St.Louis.
And...... these cars were NOT built in VIN order regardless of plant. ;-)