['Mater]

LockDoc,
Iowa Code 321.37 DISPLAY OF PLATES.
2. Registration plates issued for a motor vehicle which is model
year 1948 or older, and reconstructed or specially constructed
vehicles built to resemble a model year 1948 vehicle or older, other
than a truck registered for more than five tons, motorcycle, or truck
tractor, may display one registration plate on the rear of the
vehicle if the other registration plate issued to the vehicle is
carried in the vehicle at all times when the vehicle is operated on a
public highway.

Does not cover our trucks, need to have two to keep you in good graces with the law.