How do you check your vehicles VIN number against an OEM number?

The VIN number (Vehicle Identification Number) is located just below the driver's side of the windshield on the dash. It is also located on the driver's side door jamb near the latch. It is also on your registration and title paperwork. Any mismatch and you have a problem. OEM is the Original Equipment Manufacturer's Number. Same thing. Some cars that are build later in the season may have a modification that is incorporated in the middle of the season. It is not a requirement to add those changes to earlier models unless it is a safety issue. Example: Carburetors may be provided from different manufacturers during the season. There's a tab on the carburetor that identifies the manufacturer's OEM. Rear-ends (differentials) also have an OEM number for gear ratio identification. There are other examples and reasons.