1971 Florida era license plate

Here in Colorado you can use Year of Manufacturer Plates But you have to have a pair and you fill out a form and send it in. I did and never heard anything. I sent it in again and they sent it back saying they needed me to send photos of the plates with the request. (No where on the website does it say anything about photos) so I did and they sent me the proper registration papers. Downsides here in CO, 1. you can only drive with those plates on while going to or from a car show, parade or other "Official" event. 2. you have to keep your regular plates in the car at the same time, 3. keep the registration for the plate and the registration for the car in the car at the same time. 4. has to be plate from year of car manufacturer (that one I understand) ---GOT TO LOVE OUR GOVERNMENT!