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).Again, a neck was stamped with either the new type of code or the old date stamp, but not both.
For Stratocasters it is 22 and for Precision Basses it is 5.
The other three digits (320) are a mystery and perhaps are some kind of batch or lot number. Here’s our P-Bass again (s/n 277983) with the code 529129B.
The new code consisted of 6, 7 or 8 digits and was usually stamped in green ink.
An example of this type of neck code found on a Precision Bass is 529129B.
Now that these instruments are hitting the "magical" 25-year mark, they have suddenly gained attention.