One plausible explanation is the use of leftover necks – Fender is known to have done this often.
If you have a guitar or bass with this first style green code and you would like to submit it to the database I’m compiling, please send the model, serial number, code, and if you have them, the pot dates and pickup dates.
However, the interpretation of the two date code systems appears to be relatively straight forward and the conclusions were confirmed by pickup dates and pot dates in most cases.
To clarify, a neck would have one or the other type of stamp… It is not known why Fender used two completely different systems at the same time.
Then in 1972, Fender changed to a new type of neck stamp which had 8-digits which was stamped in green or red ink.
In 1969, CBS-Fender began to implement a new type of neck stamp in place of the usual date stamp consisting of model code, month, year, neck width (e.g.
8 DEC 65 B for a Duo-Sonic II with a 1 5/8 inch neck width).