White/GMC WHL Headlight Bulb Size

The White/GMC WHL headlight bulb uses 9004 and H6024 sizes for both high beam and low beam applications. The replacement chart covers vehicle production spanning 1988 to 1995 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.

High Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1988-1995	9004 (With Composite Headlamps)	HB1	Check Price
1988-1995	H6024 (With Sealed Beam Headlamps)	H6024	Check Price

Low Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1988-1995	9004 (With Composite Headlamps)	HB1	Check Price
1988-1995	H6024 (With Sealed Beam Headlamps)	H6024	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament halogen bulb with P29t base. 12V, 65W/45W.	9004	Check Price
ANSI standard (US & Canada). 7-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6024	Check Price

Other Locations

Additional Notes

The White/GMC WHL carries two distinct headlamp system types across the 1988-1995 model years, each requiring a different bulb or unit. Composite headlamp-equipped vehicles use the 9004 bulb, while sealed beam headlamp-equipped vehicles use the H6024 unit.
The 9004 is a dual-filament halogen bulb operating at 12V with a wattage rating of 65W on the high beam filament and 45W on the low beam filament. It uses a P29t base and conforms to ANSI standards applicable in both the United States and Canada.
Because the 9004 contains two filaments within a single bulb, it serves both the high beam and low beam functions simultaneously. This design is common in single-lamp-per-side composite headlamp assemblies where one bulb handles both lighting modes.
The H6024 is a 7-inch round sealed beam unit rated at 12V and also meets ANSI standards for the United States and Canada. 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 sealed beam format integrates the lens, reflector, and filament into one sealed glass unit. This construction means the optical housing and the light source are a single non-separable assembly.
The 9004 and H6024 are not interchangeable. Each corresponds to a fundamentally different headlamp housing design, and the fitment of one cannot substitute for the other regardless of the model year within the 1988-1995 range.
Both bulb types are listed identically for both the high beam and low beam sub-parts across all covered years, indicating that the WHL does not use separate bulbs for each beam function; the selected headlamp type handles both roles within its respective system.