The White/GMC WXLL high beam and low beam headlight bulb size specifications include 9004 and H6024 bulb options. The replacement chart covers vehicle production years from 1988 to 1995 with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The White/GMC WXLL used two distinct headlamp system types across the 1988-1995 model years: composite headlamps and sealed beam headlamps. The correct bulb size depends entirely on which system is fitted to a given vehicle.
The 9004 is a dual-filament halogen bulb operating at 12V with a wattage rating of 65W on high beam and 45W on low beam. It uses a P29t base and conforms to the ANSI standard applicable in the United States and Canada.
Because the 9004 handles both high and low beam functions through two separate filaments within a single bulb, it serves both the High Beam Headlight and Low Beam Headlight positions on White/GMC WXLL units equipped with composite headlamps.
The H6024 is a 7-inch round sealed beam unit rated at 12V and recognized under the same ANSI standard. Unlike the 9004, the H6024 is not a replaceable bulb; the entire sealed unit is replaced when the light fails or is damaged.
The H6024 similarly covers both the high beam and low beam functions on WXLL vehicles fitted with sealed beam headlamps, consistent with the dual-function design of 7-inch round sealed beam units.
The 9004 and H6024 are not interchangeable. One is a halogen capsule bulb designed for a composite reflector housing, while the other is a self-contained sealed beam assembly. Substituting one for the other is not possible without changing the headlamp housing itself.