There are several ways to determine when a Fender amp was produced.
First use the cosmetic features to get a range of possible years.
Early silver face amps: Part 2 went into this topic in some detail, but since that article was printed, I have been asked a of questions about this subject.There still seems to be some confusion about how to distinguish between a silverface Fender amp that has the desirable AB763 circuit and one that has the less-desirable AB568/AC568 circuit.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.The next one or two numbers are the month where January is 1 and December is 12. Example: AB763 = second revision, July, 1963 AA1070 = First revision, October, 1970 Misc Dating Info: Silver face amps with the aluminum trimmed grilles are from 67 or 69.
The fist Master volume controls were first installed in 72.All of the amps would have the aluminum grill trim and they may or may not have the thin black vertical lines on the control panel.One clue that can be used is the ink stamped chassis date code that is usually located in the chassis, but is sometimes found on the underside of the chassis behind the tubes.Remember, your amp is newer than the newest component.So if you find pots from late 68 and transformers from early 69 you can be pretty sure your amp is a 1969.The raised “Fender” grille logo lost its tail around 76.