(Stratocaster) Between 19 there were periods that this is not consistently done.Although a serial number is helpful for roughly determining the age of a guitar, this is often not the exact date.At the Stratocasters from the early fifties the serial numbers were stamped on the back vibrato cover.
Also overlap of serial numbers and dates come with regularity.
The next table shows the most common Fender serial numbers schemes from 1976 to the present.
Here is the S first introduced as a prefix to the serial numbers. The E stands for the decade of the eighties, and was introduced in 1979.
Usually, the production date is stamped or written is on the heel of the neck.
To read this it is necessary to unscrew the neck from the body.