You probably can decode it from the VIN, but I know you can from the door sticker (the code that's like VZN185L-GKPGKA). I don't remember the website off hand that has the chart though. You could always just lift up one rear tire, spin it twice and count the drive shaft revolutions. If it goes a little past 4, you have 4.11s, 4 1/2 you got 4.56s.