The first 5 numbers remain the same, the last 3 numbers will remain the same.

The first three numbers represent the company that made the speaker, the fourth (and fifth if there are seven numbers) represent the year the part was made, and the last two numbers represent the week that the part was made during that year.

Make note that a source code beginning with 220 was made by Jenson, 328 by Utah, 285 Rola, 137 CTS and 134 by Centralab.

While the serial numbers were randomly assigned and do not immediately tell you the age of the amp, Gibson has a large database of serial numbers that than can search to find out which year and week that your amp was made.

Always verify the serial number of a vintage Gibson amp with the company before purchasing the amp.

Factory Order Numbers (FON) with a letter from 1935 to 1941.

FON consists a batch number of usually four digits, followed by a one letter (sometimes prefixed by a space) followed by one or two digits (ranking).Les Paul Classic: This model features an ink stamped serial number with no "MADE IN USA" (just as we used on the original 1952-1960 Les Pauls).Most will be 5 to 6 digits in length, but the earliest examples feature 4 digit serial numbers.For all dates, you will need to look at the construction technique and components used to get a more precise date of manufacture.Gibson Solid Body Serial Numbers Gibson Serial numbers are located on the back of the headstock Years 1953-1961 Use the first number of the 5 or 6 digit serial number.Amps with Utah speakers are usually dated to 1945 and earlier, and Rola speakers from the late 1940ss and early 1950s.