GMC C7000 Headlight Bulb Size

GMC C7000 headlight bulbs utilize H6054, H5001, and H6024 sizes for high beam applications and H6054, H5006, and H6024 sizes for low beam applications. The replacement chart covers 1979 to 1990 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

Years	Bulb Type	Shop
1989-1990	H6054	Check Price
1989-1990	H5001 (Tiltmaster)	Check Price
1984-1988	H5001 (Tiltmaster)	Check Price
	H6054 (With 2 Rectangular Headlamps)	Check Price
	H6024 (With 2 Round Headlamps)	Check Price
	H4651 (With 4 Rectangular Headlamps)	Check Price
1979-1983	H6054 (With 2 Rectangular Headlamps)	Check Price
	H6024 (With 2 Round Headlamps)	Check Price
	H4651 (With 4 Rectangular Headlamps)	Check Price

Low Beam Headlight

Years	Bulb Type	Shop
1989-1990	H6054	Check Price
1989-1990	H5006 (Tiltmaster)	Check Price
1984-1988	H5006 (Tiltmaster)	Check Price
	H6054 (With 2 Rectangular Headlamps)	Check Price
	H6024 (With 2 Round Headlamps)	Check Price
	H4656 (With 4 Rectangular Headlamps)	Check Price
1979-1983	H6054 (With 2 Rectangular Headlamps)	Check Price
	H6024 (With 2 Round Headlamps)	Check Price
	H4656 (With 4 Rectangular Headlamps)	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). 5x7-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6054	Check Price
ANSI standard (US & Canada). 4-inch square sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5001	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
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4651	Check Price
ANSI standard (US & Canada). 5.75-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5006	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656	Check Price

Other Locations

Additional Notes

The GMC C7000 (1979-1990) uses sealed beam headlight units across all listed model years. Sealed beam units integrate the filament, reflector, and lens into a single assembly, meaning the entire unit is replaced rather than an individual bulb.
The H6054 is the most widely used headlight unit across the C7000 specifications, serving as both the high beam and low beam in 2-rectangular-headlamp configurations from 1979-1990. It is a 5x7-inch rectangular sealed beam unit operating at 12V.
The H6024 is a 7-inch round sealed beam unit used in 2-round-headlamp configurations from 1979-1988. Like the H6054, it functions as both the high and low beam within its respective headlamp system, operating at 12V.
The Tiltmaster variant of the GMC C7000 uses a distinct set of sealed beam units. The H5001, a 4-inch square unit, handles the high beam, while the H5006, a 5.75-inch round unit, handles the low beam. These differ in both shape and size from the units used in non-Tiltmaster configurations.
In 4-rectangular-headlamp configurations from 1979-1988, the high beam and low beam functions are split between two different bulb types. The H4651 serves the high beam position and the H4656 serves the low beam position. Both are 4x6-inch rectangular sealed beam units operating at 12V, but they are not interchangeable due to their dedicated beam functions.
The H4651 and H4656 share the same physical 4x6-inch rectangular format, which can create a risk of incorrect installation. Despite their similar form factor, each unit is wired and optically configured for a specific beam position, and substituting one for the other would result in incorrect light output.
The Tiltmaster variant entries first appear in the specifications for 1984-1990, while the 4-rectangular-headlamp and 2-round-headlamp configurations are documented from 1979-1988, reflecting distinct headlamp system options across the C7000 lineup.
All sealed beam units listed in the C7000 specifications conform to ANSI standards applicable in both the United States and Canada, indicating standardized optical and electrical performance requirements across the headlamp types used in this vehicle.