We have something similar here in Arizona, they call it Historical Motorcycle plate .
Bike must be at least 25 years old as well .
I've got one on my '81, and I was over by MrRiden/Rich about a week ago to take his Hall Effect sensor over to him, and Rich has the same type plate on his LS .
The cost is $10 a year more but with the collector insurance I have, it exempts me from annual exhaust emissions testing, which is $20 a year .