Harley-davidson-Factory HD 1903-1951 Part Numbers Cross Reference Manual

The Harley-Davidson Factory HD 1903-1951 Part Numbers Cross Reference Manual is a handy resource for identifying and comparing part numbers on early Harley-Davidson motorcycles. Whether you're planning a restoration, hunting for replacement parts, or sorting through vintage components, a catalogue like this helps link factory numbering to the parts you're looking into. Its real value is in supporting careful identification—especially when older references, supplier listings, and workshop records use different numbers for what appear to be similar items.

Unlike a maintenance or repair manual, a parts cross-reference catalogue generally focuses on identification rather than diagnostics, adjustment procedures, or torque specs. Use it alongside model-specific service literature when evaluating components or preparing mechanical work. The 1951 reference is especially useful for owners, restorers, and collectors researching Harley-Davidson parts from the period named in its title. It's still important to check a listed number against the motorcycle's model and production year before ordering or fitting any replacement. The PDF is available for download.