I tried to search to see if this informative GM link was posted previously but I could not find it.
I probably even got it from this site ,can't remember.
As the Subject line states:
To obtain the latest electronic controller calibration information for your vehicle.
All you need is your V.I.N.

Heres the link:
http://tis2web.xw.gm.com/tis2web

 

Thanks, now how do I tell if my car is up to date or not?