The Harley-Davidson FXSTC Softail Custom headlight bulb uses 9003 and H5006 sizes for both high and low beam functions. A replacement chart covering 1987 to 2010 contains vehicle production years paired with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 9003 bulb is a dual-filament halogen type, meaning a single bulb serves both high beam and low beam functions through two separate filaments within one housing. It operates at 12V with a 60W filament for high beam and a 55W filament for low beam, and it uses a P43t base for mounting.
The H5006 is a 5.75-inch round sealed beam unit rather than a replaceable bulb. When this unit fails, the entire assembly is replaced rather than an individual bulb element. It operates at 12V.
Both the 9003 and H5006 are classified under ANSI standards applicable to the United States and Canada.
The Harley-Davidson FXSTC Softail Custom used the H5006 sealed beam unit across the 1987-1991 model years for both high beam and low beam positions.
From 1993 onward through 2010, the FXSTC Softail Custom transitioned to the 9003 halogen bulb for both high beam and low beam positions.
Because the H5006 is a sealed beam unit and the 9003 is a separate replaceable halogen bulb with a P43t base, the two types are not interchangeable. A vehicle fitted with a sealed beam headlight housing requires a different physical assembly than one designed for a socketed halogen bulb.
The shift from H5006 to 9003 represents a change in headlight technology between the 1991 and 1993 model years, moving from a sealed beam format to a halogen bulb-and-housing format.