I have a similar 66cm CAAD 5, with a 2009 build date. I think the 66cm frames are completely different animals, being that they were available as a frameset only. I think they welded them up and let them sit in inventory for years until they were sold when they would paint and serial number them. Mine doesn't have any CAAD decals, whatsoever, just the Cannondale and Handmade in USA decals. The only way to tell what it is was to compare the unique rear dropout shape of the CAAD 5 bikes in the catalog. In any event, the frame is sweet and it's my go-to bike. Very fast, and tons of fun. It's also the first frame that's actually fit me, so I don't care what CAAD version it is! It's a keeper.