Harley-Davidson vehicle identification numbers are either found on the frame or the engine, depending on the model year of the motorcycle. In some cases, the vehicle identification number is found in both places.
On Harley models made before 1961, the engine number is the vehicle identification number. On models from 1962 to 1969, the engine number on the left-side engine case serves as the vehicle identification number. Harley-Davidsons made between 1970 and the present have vehicle identification numbers on the frame of the motorcycle, but it may also be on the engine frame. The vehicle identification number may also differ based on the information contained within it, since the way the number is written has changed.