Dating vintage Gillette razors

There was a very nice discussion with tables showing how to date Gillette razors. When I click on it the message says that it is under maintenance. It was under:

Category: Gillette Super Speed Razors
Pages in category "Gillette Super Speed Razors"

Is there another guide?

While the wiki is down, you can use the copy at archive.org: http://web.archive.org/web/20100128....com/index.php/US_Gillette_Dating_Information is the latest copy I could find. That copy is somewhat out of date, but the serial numbers and letter codes haven't really changed.