In AZ, Historic Vehicle plates (25 years or older) automatically creates registration as Class A, Non-Commercial. Regardless of weight.
A copy of the statute is a good thing to keep in the truck, along with you other docs. I've only been stopped once, here in AZ matter of fact. The officer was totally flummoxed by the ruling, took some time to wrap his head around it, but I went on my way unimpeded. Driven in CA, NV, TX without a second glance.
Almost as much fun as a Title II machinegun, observed by a new cop unfamiliar with the private ownership process...
Dennis