They are not of a concern with dating as only the 2 letter date codes on whichever chart or sticker and the transformer number comes into play for that....

There are other ways but the above is a more accurate method.

dating fender drri by serial number-19

The type of face, grille cloth, type and number of speakers, type and number of knobs, etc.

only come into play when you’re trying to value the amplifier in the Blue Book for Guitar Amplifiers per the model description that is provided.

(If you are not comfortable performing this operation, please use an experienced professional guitar tech in your area).

The serial numbers do not immediately reflect the change, as CBS continued to make instruments using existing, tooling, parts, and serial number schemes.

If you have what you consider to be a somewhat "odd" serial number, please check the following chart to see if you find your serial number configuration here.

This chart contains If you are unable to place the approximate year of manufacture of your instrument using the above charts, there are a few great books available, which have invaluable information on the history of Fender instruments.

You will notice that there is quite a bit of overlap of numbers and years.

The only way to try to narrow the date range of your specific instrument would be to remove the neck and check the butt end of the heel of the neck for a production date, which may be stamped or written there.

The "S", stood for decade of the 1970s, and began CBS' attempt to use serial numbers to identify the year of production for the piece.