It stands for Wally Byam Caravan Club International. The big red numbers you see on other Airstreams is the membership ID number of the owner. Ours, for example is 3021.
Do a search on WBCCI on this site, and you'll find out more than you'd ever want to know about the organization. It is international, and there will be a unit 'local' to your area that you can join. They will take care of your unit and International dues. You can contact the WBCCI offices at (937)596-5211 or at www.wbcci.org
to find out who to contact in your local unit.
AIR 2053 Current: 2006 Born Free 32 RQ Kodiak Chassis, & 1995 Coachmen B-van
Former Airstreams: 1953 Flying Cloud, 1957 Overlander, 1961 Bambi, 1970 Safari Special, 1978 Argosy Minuet, 1985 325 Moho, 1994 Limited 34' Two-door, 1994 B190 "B-Van"