The Third and Fourth Characters = body style.The second character is = the assembly plant.The First Character = the Year of production.The following key can be used to decode the 11-character VIN of your Mustang. I just like knowing what every character on my car’s nameplate means, whether it is 11 characters on older Mustangs or the current 17- digit/letter system used today. While obtaining that information can be a time-saving and money-saving adventure, I’m old school. Many websites can provide you with a complete vehicle history, find out where it was made, or even find out whether the car was in an accident, just by tapping a few numbers and letters into a computer. Understanding a vehicle's VIN is the key to unlocking a treasure chest of information about the car. How do you decode your classic Mustang’s VIN? You have your eye on a classic Mustang and want more information about this beauty.