Gibson Serial Number Check 'link' -

There are also separate systems for Gibson Custom, Gibson Memphis (now closed), and vintage instruments from the 1950s and ‘60s, where numbers were often stamped on the back of the headstock or inside the control cavity—sometimes inconsistently.

A nine-digit number beginning with “14” (year), then a space, then a letter indicating plant (e.g., “C” for Chicago), followed by six digits. gibson serial number check