Hi John!
Yes I know I need to update the website as I've new info gathered during a long time.
About the serialnumbers.
Yes seems there is a date code in the numbers as you wrote.
But it doesn't mean that the frames were made that month.
The dropouts were dropped in big containers and the welders took what they needed when they needed.
So, supose new dropouts were mixed with the old and in that way there is no sure way to know when a frame was made.