tatest wrote:
Chassis model years run change in autumn (October through December) of the year before what is on the VIN. This is regulated Federally. Thus 2019 chassis won't be built any earlier than October 2018, maybe not before December.
My understanding is that the only requirement for vehicle years is that the model being built on January 1st belongs to that model year. The manufacturer is permitted to change model years at any point during the year, including before October. Certainly that's the case for cars, where model years often change during the summer. Perhaps different rules apply to truck chassis.
For cars that have a moderate redesign, sometimes they do the production line changeover around New Year's Day and so end up skipping a model year, even though production was only stopped for several weeks.