All of the vehicles covered by this guide are built on a similar platform; GM calls them a W-Body. Other GM vehicles have their own platform designations. The Vehicle Identification number (VIN) plate is located on the left upper instrument panel and is visible from the outside of the vehicle at the lower left (driver's side) of the windshield. The VIN consists of 17 characters. Each sequential build unit number is prefixed by eleven letters and numbers. These numbers are an important source of identification for your vehicle and its equipment. The fourth and fifth positions of the VIN identify the model (series, this case, W-Body) and body style of the vehicle. The eighth digit is the engine code and the 10th letter represents the model year (in this case, V=1997, W=1998, X=1999, and Y=2000).