An Ampeg from 1960 would be covered in navy random flair vinyl whereas an amp from 1965 would be covered in blue check vinyl.
Another check for a 1960 versus a 1965 or later serial number (i.e.
These codes have been used on components including potentiometers (pots), transformers, capacitors, tubes, and speakers.
The code usually consists of 6 or 7 digits such as 137634 where the first two or three digits is the EIA code for the manufacturer (137 denotes CTS), the fourth digit and sometimes fifth digit denotes the year (in this case it could be 1956, 66, or 76), and the last two digits denote the week of the year.
The code contained information regarding the manufacture and date of production.These amps used a serial number system that was not used by any Ampegs.Unfortunately, the serial numbers are of little help for dating one of these pre-Ampeg models and EIA date codes on components were used sporadically during the early post WW-II years.The M-12 Mercury circuit of 1960 used 6V6 power tubes, but the Mercury circuit of 1965 used 7591As.Likewise, an Ampeg from 1954 would not be covered in blue check vinyl whereas an amp from 1964 would have this covering.