White/GMC WHLB Headlight Bulb Size

The White/GMC WHLB headlight bulb size specifications indicate that both high beam and low beam applications utilize a 9004 or H6024 bulb size. The replacement chart covers vehicle production years spanning 1991 to 1995 with corresponding bulb 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
1991-1995	9004 (With Composite Headlamps)	HB1	Check Price
1991-1995	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
1991-1995	9004 (With Composite Headlamps)	HB1	Check Price
1991-1995	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 WHLB used two distinct headlamp systems across the 1991-1995 model years: composite headlamps and sealed beam headlamps. Each system requires a different bulb type, and the two are not interchangeable.
The 9004 is a dual-filament halogen bulb operating on a P29t base at 12V, with a rated output of 65W on the high beam filament and 45W on the low beam filament. A single 9004 unit serves both the high beam and low beam functions in composite headlamp-equipped vehicles.
Because the 9004 handles both beam functions within one bulb, composite headlamp-equipped WHLB models list the same bulb size for both the high beam and low beam positions across all years in the specifications.
The H6024 is a 7-inch round sealed beam unit conforming to ANSI standards for the US and Canadian markets. Unlike the 9004, the H6024 is not a replaceable bulb; the entire sealed unit is replaced when the light source fails.
Both the 9004 and H6024 conform to ANSI standards applicable in the US and Canada, indicating standardized performance and fitment requirements for both types within those markets.
Substituting an H6024 sealed beam unit for a 9004 halogen bulb, or vice versa, is not supported by the specifications, as each bulb type corresponds to a physically and functionally distinct headlamp assembly design.
The H6024 sealed beam unit operates at 12V, consistent with standard automotive electrical systems, though the specifications do not assign separate wattage values to its individual beam functions as they do for the 9004.
The 9004 and H6024 fitment assignments remain unchanged across all five model years covered in the specifications, with no variation in bulb size by year for either headlamp system.