White/GMC WIM Headlight Bulb Size

The White/GMC WIM headlight bulb uses 9004 and H6024 sizes for both high and low beam applications. The replacement chart covers 1988 to 1994 production years 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
1988-1994	9004 (With Composite Headlamps)	HB1	Check Price
1988-1994	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
1988-1994	9004 (With Composite Headlamps)	HB1	Check Price
1988-1994	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 WIM used two distinct headlamp systems across the 1988-1994 model years: composite headlamps and sealed beam headlamps. The correct bulb type is determined entirely by which headlamp system is fitted to the 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 meets ANSI standards for the US and Canadian markets.
Because the 9004 carries both filaments in a single housing, it serves both the high beam and low beam functions on WIM units equipped with composite headlamps. A single bulb type covers both lighting positions in that configuration.
The H6024 is a 7-inch round sealed beam unit rated at 12V and recognized under ANSI standards for the US and Canadian markets. Unlike the 9004, the H6024 is not a replaceable bulb within a housing; the entire sealed unit is the component that is replaced.
On WIM units fitted with sealed beam headlamps, the H6024 handles both the high beam and low beam positions across all seven model years listed, mirroring the same dual-position role that the 9004 fills on composite-equipped vehicles.
The 9004 and H6024 are not interchangeable. One is designed for composite headlamp housings and the other is a self-contained sealed beam unit, meaning the physical mounting, electrical connection, and replacement procedure differ between the two systems.