The White WIM headlight bulb size chart specifies high beam and low beam bulb options including 9004, H6024, H4651, and H4656 sizes for this heavy-duty truck model. The replacement chart covers 1984 through 1988 vehicle production years 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 9004 is a dual-filament halogen bulb rated at 12V with a 65W high beam filament and a 45W low beam filament, fitted with a P29t base. Its dual-filament design allows a single bulb to serve both the high beam and low beam functions within a composite headlamp assembly.
The White WIM uses the 9004 bulb for both high beam and low beam positions in conventional and composite headlamp configurations across the 1984-1988 model years, making it the most frequently specified bulb type in these specifications.
The H6024 is a 7-inch round sealed beam unit operating at 12V. It is not a replaceable bulb in the conventional sense; the entire sealed unit is substituted when replacement is required. It appears on the White WIM (1988) in configurations equipped with sealed beam headlamps.
The H4651 and H4656 are both 4x6-inch rectangular sealed beam units operating at 12V, and both follow the same whole-unit replacement requirement as the H6024. The H4651 is specified for the high beam position, while the H4656 covers the low beam position in non-conventional configurations for the 1984-1987 model years.
Because the H4651 and H4656 share the same physical 4x6-inch rectangular sealed beam format, they are not interchangeable despite their similar appearance. Each unit contains a filament arrangement optimized for its designated beam position, and substituting one for the other would result in incorrect light output.
The 1988 model year represents a transitional point in the specifications, where the headlamp configuration determines the applicable bulb type. Composite headlamp-equipped vehicles use the 9004, while sealed beam-equipped vehicles use the H6024, meaning the two bulb types are mutually exclusive for that year.
All four bulb types listed across these specifications conform to ANSI standards applicable in both the United States and Canada, indicating regulatory compliance across both markets for the applicable model years.