There are a number of resources available online to help you to date your guitar amplifier or bass amp.
Japanese Serial Numbers on Peghead Decal Note the lack of S, E, N series.
Guitar amplifier dating by serial numbers - How To Date A Guitar Amp or Bass Amp By Serial Number.
Below are some of the changes that occurred as a result of the CBS takeover.
Some of these changes were gradual and some were immediate, but for collectors, they are all considered steps in the wrong direction: From 1954 until 1959, most Fender guitars and basses used a pickguard made of a single piece of celluloid.
Starting in 1959, most Fender pickguards consisted of three layers of celluloid with a top layer that added a certain greenish hue.
In 1965, the switch was made from celluloid to ABS or vinyl; these guards are considered far less attractive by most collectors. With the introduction of the Stratocaster in 1954, Fender set a precedent for sleek body contours that would carry through the Jazzmaster, Jazz Bass, Jaguar and beyond.
Things began to change in late 1964 and the period from then until the beginning of 1966 is usually considered the “transition” period.
Guitars from this era can be identified by their use of a serial number beginning with an L.
The changes brought about by the CBS purchase of Fender created a sharp divide in the history of the one of world's most iconic guitar makers.
Post-1965 Fenders are automatically accepted as inferior instruments, and there are many collectors who simply will not consider purchasing anything made after the buyout.
Please keep in mind that those components must be original to get a valid date for a vintage guitar amplifier.