Most post tweed Fenders had trannys manufactured by Schumacher.
They used a code like this: 606 – 645 The date is in the last three digits, after the 606 – .
Electronic components such as transformers, potentiometers, speakers, and some capacitors are often stamped with a date code, which indicates the manufacturer and the manufacturing date.
The code follows the format: = a number from 1 - 52 indicating the week of manufacture.
Let’s take a look at a couple speakers from Warehouse Guitar Speakers (wgs4.com) so I can better explain this.