GMC C5000 Headlight Bulb Size

GMC C5000 headlight bulbs utilize H6054, H6024, and H4651 sizes for high beam applications, with H6054, H6024, and H4656 sizes for low beam configurations. The replacement chart covers 1979 to 1990 production 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
1979-1988	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
1979-1988	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). 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). 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 C5000 uses sealed beam headlight units across all specified model years, meaning the entire lens-reflector-filament assembly is replaced as one unit rather than replacing an individual bulb inside a housing.
The H6054 is a 5x7-inch rectangular sealed beam unit operating at 12V and conforming to ANSI standards for the US and Canada. It serves as both the high beam and low beam unit on 2-rectangular-headlamp configurations of the C5000 from 1979-1990.
The H6024 is a 7-inch round sealed beam unit operating at 12V under the same ANSI standard. It covers both high beam and low beam functions on C5000 models from 1979-1988 equipped with 2 round headlamps.
On C5000 models from 1979-1988 fitted with 4 rectangular headlamps, the high beam and low beam positions use different sealed beam units. The high beam position takes the H4651, while the low beam position takes the H4656. Both are 4x6-inch rectangular units rated at 12V.
The H4651 and H4656 share the same 4x6-inch rectangular form factor and ANSI rating, but they are not interchangeable between positions. Installing the wrong unit in either the high beam or low beam socket of a 4-lamp system would result in incorrect fitment for that position.
For the 1989-1990 model years, the specifications list only the H6054 for both high beam and low beam, with no headlamp configuration qualifiers noted. This indicates those years were offered solely with the 2-rectangular-headlamp arrangement.
All four sealed beam types referenced in these specifications, H6054, H6024, H4651, and H4656, comply with ANSI standards applicable in both the United States and Canada, reflecting a standardized sizing system that allows cross-brand sourcing of replacement units.
Because the headlamp configuration of a given C5000 unit determines which sealed beam type is required, confirming whether the vehicle has 2 round, 2 rectangular, or 4 rectangular headlamps is a necessary step before sourcing a replacement for 1979-1988 model years.