Just to close out this thread. A helpful New Jersey Chevy dealer(not the one who did the faulty installation of the ignition switch)did some research and got the answer of April 2006 - same as the date of manufacture for the car. Apparently 6 refers to 2006 and 10 2 could be the 102nd day of the year or April 12. it's remarkable that the battery lasted almost 9 years.
2006 Cobalt LT Sedan 2.2L Automatic Laser Blue
Last edited by helixal; 01-29-2015 at 05:45 PM.