http://www.trfindley.com/pgbndxhbs.html has a bunch of info on the Bendix 2-Speed Kickback Hubs and how to overhaul them and gearing. I prefer the Sachs Torpedo my self, but a Blue band looks awesome on a 60's Stingray!

There were 3 types of Automatic Hubs, identified by band color: Red, Yellow, and Blue bands. The Red Band was made 1962-1964. The Yellow and Blue Bands were made 1965-1969.

The red and yellow band hubs have a low gear: 1 sprocket turn for .67 hub turn to go up hills easier. High gear is 1:1. The hubs would go on bikes with 26" and 24" wheels. They were also used on bikes with 20" wheels and 52-teeth sprockets. The red and yellow hubs have some different parts in them that won't interchange. Check the diagram for the different brake parts of each hub.

The blue band has 1:1 low gear, and high is overdrive: 1 sprocket turn for 1.5 hub turn. These are used on bikes with 20" wheels and 36-teeth sprockets to go further on flat roads.