Here in Calif. the deal is............
You hafta have a matched pair.
The number cant be in use on anything else in the state.
You hafta give the DMV a buncha money and fill out all their stupid forms.
You hafta jump thru all their hoops and smile while youre doing it,,and give them more money.
Then you get to enjoy your YOM (year of manufacture) license plates. Plus pay more,extra money when you re-new your reg. every year.
Its a great system. I love it so much,,I have them on all 3 of my old trucks.