According to Rule, the G prefix was added as a result of a government requirement.
The following is a cut and paste, don't recall the source, but it agrees with the SNs on my M70s::
The last serial numbers listed in the Winchester DOM documents goes to 1992, and that is "G2037985". As you can see, that is a 7 digit serial #. The classics started with a 5 digit serial # in 1992. 6 digits were built from about 94-99, 7 digits were 2000-2006 etc. etc.... Now the new ones (BACO) started with 35AMP....(2008 models). You'd have to check with BACO to see what they were after 2009.
When Classic's started in '91 they started at G1 or G1000 somewhere around there. They continued their progression until beginning of 2003 when something big happened. Don't know what but one of the things that changed was Classic's went from around G380000 to seven digits overnight. Just so happens that is the exact same time quality fell off the ledge.
Pre '64's/'68's didn't have a G.
Five digit Classic's went till about late '94, six digits through 2002
