Commencing in September 1980, Motor Vehicle Safety Standard regulation FMVSS-115 required a 17-digit VIN (vehicle identification number) on all new vehicles sold in the United States. (In Canada, the applicable regulation is Motor Vehicle Safety Regulations Standard 115 of the Motor Vehicle Safety Act.) In June of 1983 the American requirements of the regulation moved to Part 565.

The vehicle identification number is divided into four parts: the World Manufacturer's Identification (WMI - three characters); the Vehicle Description Section (VDS - five characters); the check digit; and the Vehicle Identification Section (VIS - eight characters). When decoded, the VIN tells the country and year of manufacture; make, model and serial number; assembly plant and even some equipment specifications.

Note that the sort sequence for characters in the VIN is A to Z, then 1 to 9, and finally 0, with the letters "I", "O" and "Q" not normally used.

The following is not an exhaustive list, but I have managed to compile a listing for the manufacturers of most types of buses and service vehicles operated by many transit companies, as well as specific codes for several major manufacturers.

One of the better free online VIN decoders that I've found is at CarFax.com

To check your VIN number for reports and info about your auto.
Go to: http://www.carfax.com/