The White/GMC WXLM headlight bulb uses 9004 and H6024 sizes for both high and low beam applications. The replacement chart covers 1991 to 1993 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The White/GMC WXLM used two distinct headlamp system types across the 1991-1993 model years: composite headlamps and sealed beam headlamps. Each system requires a different bulb or unit, and the two are not interchangeable.
The 9004 is a dual-filament halogen bulb operating at 12V with a high beam output of 65W and a low beam output of 45W. Its P29t base is a proprietary connector, meaning it is not pin-compatible with single-filament halogen types.
Because the 9004 carries both filaments within a single bulb, it serves both the high beam and low beam functions in WXLM units fitted with composite headlamps, rather than requiring separate bulbs for each function.
The H6024 is a 7-inch round sealed beam unit rated at 12V. Unlike the 9004, it is not a replaceable bulb housed within a separate lens assembly. The entire unit, including the lens, reflector, and filament, is replaced as one piece.
The H6024 also handles both high beam and low beam functions in WXLM units fitted with sealed beam headlamps, mirroring the dual-function role of the 9004 in composite systems.
Both the 9004 and H6024 conform to ANSI standards recognized in the United States and Canada, placing them within a regulated performance and dimensional framework applicable to the North American market.
Owners of the WXLM with composite headlamps who attempt to install an H6024 unit, or vice versa, would face a fundamental incompatibility, as the two systems differ in housing design, base type, and replacement method.