GMC P60 Headlight Bulb Size

The GMC P60 high beam headlight uses bulb sizes H6054, H6024, or H4651, while low beam headlight applications require H6054, H6024, or H4656 bulb sizes. The replacement chart covers 1983 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 Size
1989-1990	H6054
1985-1988	H6054 (With 2 Rectangular Headlamps)
	H6024 (With 2 Round Headlamps)
	H4651 (With 4 Rectangular Headlamps)
1984	H6054
1984	H4651 (With 4 Rectangular Headlamps)
1983	H6054 (With 2 Rectangular Headlamps)
	H6024 (With 2 Round Headlamps)
	H4651 (With 4 Rectangular Headlamps)

Low Beam Headlight

Years	Bulb Size
1989-1990	H6054
1985-1988	H6054 (With 2 Rectangular Headlamps)
	H6024 (With 2 Round Headlamps)
	H4656 (With 4 Rectangular Headlamps)
1984	H6054
1984	H4656 (With 4 Rectangular Headlamps)
1983	H6054 (With 2 Rectangular Headlamps)
	H6024 (With 2 Round Headlamps)
	H4656 (With 4 Rectangular Headlamps)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). 5x7-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6054
ANSI standard (US & Canada). 7-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6024
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4651
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656

Other Locations

Additional Notes

The GMC P60 uses sealed beam headlight units across all listed model years (1983-1990), meaning the entire lens-and-filament assembly is replaced as one unit rather than swapping an internal bulb.
All sealed beam types specified for the P60 conform to ANSI standards recognized in both the United States and Canada, and all operate at 12 volts.
The H6054 is a 5x7-inch rectangular sealed beam unit that serves as both the high beam and low beam source on two-rectangular-headlamp configurations, as a single unit handles both functions.
The H6024 is a 7-inch round sealed beam unit fitted to P60 models equipped with two round headlamps, covering both high and low beam positions with the same part number.
On four-rectangular-headlamp configurations, the H4651 and H4656 are not interchangeable despite sharing the same 4x6-inch rectangular form factor. The H4651 is designated for the high beam position, while the H4656 is designated for the low beam position.
The 1984 GMC P60 is a notable fitment case, as its two-headlamp configuration lists only the H6054 without a round-headlamp variant, unlike the 1983 and 1985-1988 model years which include an H6024 round-headlamp option.
The 1989-1990 P60 models list only the H6054 for both high and low beam positions, with no headlamp-configuration qualifiers, indicating a single headlamp system for those years.
Because the H4651 and H4656 share the same physical size, installing the wrong unit in a four-lamp system would place an incorrect beam pattern in a given position, making position-specific selection critical for four-rectangular-headlamp P60 configurations from 1983-1988.