No letter. If doc would have registered multiple cars the same day, he could have them in order, 1001, 1002, 1003,etc. I got my plates for two cars the same day, and mentioned that they ended in the year of two of my cars, but not both I was registering, so the gal grabbed the next plate, and swapped it for the one that didn't match the year.Interesting, so Minnesota issues separate number collector plates and no a sequential letter after the numbers. So the collector numbers are the same but each car has a sequential letter.