The code follows the format: XXXYY ZZ where: XXX = a two or three (possibly four on newer amps) digit number indicating the manufacturer.
(see chart below) YY = is a one or two digit code indicating the year.
Fender often used the same circuit for many years so this is not a very accurate method for amp dating.
Besides, no article in the Dating Fender Amps by Serial Number series would be complete without some interesting information, n’est ce pas?
I promise the tables will still be there after you finish reading.
Next, (if applicable) look for the date code on the tube chart.
If your amp dosen’t have a date code, flip the amp upside-down and check the transformers, and speakers for their manufacturer codes.
Working at FMI – I was able to interview a fellow (who wishes to remain anonymous) who worked at Fender in 1972-73 in the amp department.
Although his job was somewhat limited, his recollections provided some really fascinating insights to how the amps were built.
Okay, I know you’re all just dying to skip ahead to the serial number tables but try to contain your excitement and read through the article first.
A 1957 tweed Vibrolux was reported with a tube chart printed with circuit “5E3” (tweed Deluxe) instead of the correct 5F11 (see photo).
Some examples include a '66 Princeton Reverb and ’66 Pro Reverb with Better Coil output transformer, a ‘66 Deluxe Reverb and ‘67 Twin Reverb with Better Coil reverb transformer, and a 1968 Vibro Champ with Better Coil trannies.
These units look, and apparently sound, just like the Schumacher-made units so it’s easy to overlook that “831” code.
Fender installed casters on some larger amps and cabs beginning in 72.