1961-1969 Firebird, Les Paul, and SG reissues (since 1997):
YYRRRM
Y is the production year
RRRĀ® indicates the guitar’s place in production for that year.
M is the model being reissued
Reissue model codes:
1= SG Custom and Special
2= SG Standard
3= 1963 Firebird 1
4= 1964 Firebird III
5= 1965 Firebird V & VII
8= 1968 Les Paul Custom

Examples: 050102 is the 10th SG Standard reissue produced in 2005.
030084 is the 8th 1964 Firebird III reissue produced in 2003.

Newer Gibson SG Custom Reissues are trying to stay true to the 6 didget serials from the 60s that start with 0. So for 2011 it starts with 01, 2012 02 and so on…