Farm plates are good for only "farm" trucks. That means you must have a agriculture (Agg) exemption to qualify. If you will go to any county registration office, they will have a book showing the plates (color and sizes). I don't believe there was a challenge to anyone wanting commercial plates back then, just farm plates. You probably would need to see if they had specific "truck" plates. I tried to use non truck plates and was refused. I finally found truck plates and that passed inspection.
