OF crew - I want to share the expansion of my serial number project around the "Type XX" (well, the 3-register evolution). I started with the Mathey-Tissot, and have now added Girard-Perregaux, along with comments on dial, movement and bezel (images to come, along with sections on case and hands). I'll be adding the same information for Breguet once the section and images for MT and GP are complete. This serial number project includes information for every 3-register Girard-Perregaux Type XX I have seen on the web, including instagram, and is categorized by serial number plus traits of the watch, including dial type, caseback, hands, etc., with the ability to search, sort and filter the information. If you are willing to share any Type XX (3 register) information you have (for your watch or others you have found) to help me as I keep building my project, please feel free to reach out. Not many of these around. And feedback is always welcome! http://alphahands.com/vintage-watch...y-tissot-girard-perregaux-breguet-3-register/ Happy Friday everyone- Norm