Gibson — Serial Number

Let me give correct Gibson example: 90123345 Digit1=9 (1979 or 1989) Digit5=9 (matches) 012 = Jan 12 345 = unit 345. Same format, but first digit and fifth digit both same number. Example: 91234567 = 2009? No — 91234567: digit1=9, digit5=6? Mismatch. So invalid.

Actually Gibson confirms: 2005-2014: YDDDYRRR where Y is last digit of year, and fifth digit is same Y. So year is 197Y, 198Y, 199Y, 200Y. gibson serial number

Example: 81234567 → first digit 8 = 2008? 1978? If fifth digit=1? fails. So invalid. Let me give correct Gibson example: 90123345 Digit1=9