Fender Tube amp codes:
1953-1970 - (look for a 2 letter code stamped on the tube chart inside the back of the amp)- the first letter is the year, and the second letter is the month. An amp stamped NA would have been made in Jan. of 1964. Here is a list of the first letter showing the year of manufacture.
These codes have nothing to do with the serial number that is stamped on the right rear of the chassis - Those numbers are posted below.

    A=1951, B=1952, C=1953, D=1954, E=1955, F=1956, G=1957, H=1958, I=1959, J=1960,
    K=1961, L=1962, M=1963, N=1964, O=1965, P=1966, Q=1967,R=1968, S=1969, T=1970
A=Jan, B=Feb, C=Mar, D=Apr, E=May, F=Jun, G=Jul, H=Aug, I=Sep, J=Oct, K=Nov, & L=Dec

• "Pre-CBS" Blackface Amps are labeled "Fender Electric Instruments". 
  After CBS bought Fender in 1965, amps were labeled "Fender Musical Instruments". 

• Early Fender Electric Blackface amps from 1964 and some into early 1965 
  did not have a Fender Logo on the grillcloth.

• "Pre-CBS" Blackface Original Amp Knobs have the set screw at the number "10"

• Fender Blackface amps & early Silverface amps used cloth covered wire
   until sometime in 1968

• Silverface amps with aluminum trim surrounding the grill cloth are 1968 models
  Silverface Amps began in 1968, when Fender made circuit changes to most amps, 
  making them a little less desirable than the blackface amps.
  A good amp tech can make these sound great.

• In 1973, Fender removed the "Tail" from the logo.

• A push-pull pot was added to some amps in 1974. 
  Therefore, if you have a push-pull pot, your amp is 1974 or newer. 

1970-1989 -Most amps do not have a date code stamped on the tube location chart. These codes are for amps with the serial number beginning with a letter:

B+5---digits - 1975-1976
A6+5-digits - 1976
A7+5-digits - 1977
A8+5-digits - 1978
A9+5-digits - 1979
F0+5--digits - 1980
F1+5--digits - 1981
F2+5-digits - 1982/83
F3+5-digits - 1983/84
F4+5-digits - 1984/85
F9+5-digits - 1979-1980

EIA numbers taken from the transformers may help you to determine the date of production on amps that fall between the different dating schemes. These numbers always begin with "606", and are followed by three or four digits in various combinations. If three digits are present, the first digit would refer to the year i.e. ("7" would mean 1967). If four digits are present, the first two digits refer to the year i.e. ("66" would mean 1966). The last two digits would refer to the week of the year i.e. ("26" would mean the 26th week or approximately June). An example would be: EIA 606-4-21 would mean the 21st week of 1964.

All Fender amplifiers, manufactured after 1989 include a date code on the amplifier.
This code is located on the "QA" (Quality Assurance) sticker, which may be found on the back of the amp chassis. The sticker is a Black and Silver label, which contains several lines for "sign-offs" at the completion of sound and electrical tests, where applicable. The last line will have 2 letters of the alphabet either printed or written by hand. Good luck reading some of the hand written ones. These letters are the production date code for the amplifier. The first letter refers to the year, and the second letter refers to the month of manufacture. The codes are:
1990-A / 1991-B / 1992-C / 1993-D / 1994-E / 1995-F / 1996-G / 1997-H / 1998-I / 1999-J / 2000-K 
2001-L / 2002-M / 2003-N / 2004-O / 2005-P / 2006-Q / 2007-R  / 2008-S / 2009-T / 2010-U / 2011-V
2012-W / 2013-X / 2014-Y / 2015-Z

                  FENDER AMP Chassis Serial Number DATE CODES

These are the numbers you will find stamped into the chassis.

A few books are available for dating Fender amps, which have  information on the history of Fender amplifiers. You will need to get the date codes from the speaker frames, the potentiometer date codes, the transformer codes and as much other detailed information you can about the specs and features of your amp. If you have a serious interest in learning about the history of Fender amplifiers, or if you just want to try to establish the year of production of your own amp, I recommend that you pick up the following book.

"Fender Amps the First 50 Years", Teagle & Sprung,
(Available through your local Superior Music store) pn# 099-5011-000, US MSRP $34.95

                                   FENDER AMP SPEAKER CODES
This chart will identify the speaker brand used in your amp.
Fender used speakers manufactured by the following companies:

• Altec-Lansing -#391
• CTS - #137
• Electro-Voice -#649
• Eminence -#67
• Jensen - #220
• JBL #73
• Oxford - #465
• Rola -#285
• Utah -#328