Was it manufactured with a licese plate light?

I have a 1989 Ford Mustang, 138,000 miles. I have been told that all cars are manufactured with a license plate light. But it doesn't have one. We are the second owners of this car, but the first owner was a relative and we are sure he did not remove a light. Is it possible that it was not made with a light there? I only ask due to a conversation with a police officer who pulled me over for the not having one.