Maybe this will be a better source for ya
http://www.ringling.com/ContentPage.asp ... tion=45823
from RBBB's FAQ section
13. What is the difference between the Red Unit and the Blue Unit?
Each year that The Greatest Show On Earth comes to your area, the show is entirely different and completely new! We have two traveling units -- the Red and the Blue -- that each tour North America 11 months out of the year. Each unit tours for two years, returning to Winter Quarters on alternate years to prepare a brand-new edition of Ringling Bros. and Barnum & Bailey. How can you tell the difference between the Red Unit and the Blue Unit? The Red Unit presents the odd-numbered editions of The Greatest Show On Earth, while the Blue Unit presents the even-numbered editions. Both units travel roughly the same tour schedule around the country, so if you saw the Blue Unit last year, you'll see the Red Unit this year. In all cases, every time The Greatest Show On Earth comes your way, rest assured it's an all-new production that's never been to your city!
No mention of the Gold unit, its a different show and not one of the two "Greatest Shows on Earth" that travel by train.
I caught the entire train moving through Penn Station NY about a month ago, going from LI to NJ. Its always such a cool thing to see it up close. Its also fun seeing the performers and workers taking videos from the vestibules of where they are going to and through and of all the people watching the train and them travel by!