Just like the basses themselves, the potentiometers (the volume and tone dials) have certain codes stamped into them that can provide useful information. These are an invaluable tool for dating vintage Gibson Instruments. The Gibson serial number system can be very difficult to interpret to say the least - whilst the pot codes had a simple system in which the date of manufacture was encoded into the numbers stamped into the casing. Usually on the back, as shown in the picture here, or sometimes on the side.
How to Read Pot Codes
Most Gibson basses use pots made by a company called CTS (Chicago Telephone Supply), which has a manufacturers code of 137. CTS codes are in the format 137-year-week. So in the example pictured 1377719 would indicate a CTS pot, manufactured in the 19th week of 1977. Gibson did use pots by other manufacturers, but less often - one such manufacturer is Centralab, code 134, which appears on a lot of early 60s guitar pots. For example a Centralab pot with code 1346102 would indicate a production date of the second week of 1961.
The other number on the pot 70-031 is the Gibson part number. For more information about part numbers, and ratings, see the VintageGuitar Gibson Pot Database
When dating an instrument using pot codes, it is important to remember that pots can be changed, or fitted way after they themselves were made, so any conclusion must be in line with other features, such as hardware and serial numbers.
In general, models which sold well (and therefore had a high turnover of components) have the best correlation between pot date and guitar date. In these cases all pots are often from the same batch, with identical codes. For example something like an EB0 which sold in it's thousands will typically have pots produced contemporaneously with the guitar, especially during the 1960s and early 70s. On the other hand, a model with low production volume, perhaps like the EB-0F, may well have pots produced some time before or after the body/neck; some looms being comprised of pots with significantly different dates.
One thing you can always be sure of (assuming the pot is original): no guitar can have been shipped BEFORE a potentiometer date
Gibson bass potentiometers for sale
1970 USA GIBSON EB BASS GUITAR HARNESS POTS JACK EB-O Parts
Plano, Texas, 750**, UNITED STATES OF AMERICA
$350
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1970??s USA GIBSON EB BASS GUITAR Wiring HARNESS POTS JACK EB-O
Houston, Texas, 770**, UNITED STATES OF AMERICA
$145
The brand of the harness is Gibson, and it is an exact fit for EB Bass Guitars. The item has not been modified in any way and is in its... more