From 1983 onwards, you may calculate the date of manufacture by adding 50 to the two digit prefix of the serial number. Olds Serial Numbers and Dates for Trumpets and Cornets. Knowing if your Gibson banjo is a prewar or postwar model will help you understand the serial number. i got these for my 5120: Samick Plant, Korea May 2012 Production Number: 4215 Don't know where to find the serial number on your brass instrument? 85000: 1964: SN 85459 last known Reynolds serial number with Cleveland-made parts. The 1.10 series Note: From 1987 to present, add 50 to the serial number prefix to calculate the year of manufacture. Serial Number Physical Features Information #0 'Ambassador' Cornet: Bell type: Normal Bore mark: none Manufacture Location: Fullerton Est.