White/GMC WIL Headlight Bulb Size

The White/GMC WIL uses 9004 and H6024 bulb sizes for both high beam and low beam headlight applications. A replacement chart covering 1988 to 1992 model years documents the headlight bulb specifications for this vehicle.

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
1988-1992	9004 (With Composite Headlamps)	HB1	Check Price
1988-1992	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
1988-1992	9004 (With Composite Headlamps)	HB1	Check Price
1988-1992	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 WIL uses two distinct headlamp systems across the 1988-1992 model years: composite headlamps and sealed beam headlamps. Each system requires a different bulb type, and the two are not interchangeable.
Vehicles equipped with composite headlamps use the 9004 bulb for both high and low beam functions. The 9004 is a dual-filament halogen bulb, meaning a single unit serves both beam positions rather than requiring separate bulbs for each.
The 9004 operates on a 12-volt system and carries a wattage rating of 65W on the high beam filament and 45W on the low beam filament. It uses a P29t base, which is a specific connector type associated with this bulb family.
The 9004 conforms to ANSI standards recognized in both the United States and Canada, placing it within a regulated specification framework for electrical and photometric performance.
Vehicles equipped with sealed beam headlamps use the H6024, a 7-inch round sealed beam unit. Unlike the 9004, the H6024 is not a replaceable bulb; the entire lens, reflector, and filament assembly is replaced as a single unit when the lamp fails.
The H6024 also operates on a 12-volt system and meets the same ANSI standard applicable in the United States and Canada. Its round form factor is a fixed physical characteristic of the sealed beam format.
Because the 9004 and H6024 serve the same high beam and low beam positions on the White/GMC WIL, the correct replacement depends entirely on which headlamp system the specific vehicle carries, not on the model year alone.
Both headlamp system types remain consistent across all five model years covered in the specifications, with no variation in bulb size requirements from 1988 through 1992.