GMC R3500 Headlight Bulb Size

The GMC R3500 headlight bulb specifications include high beam sizes of H6054, H4701, and 9005, along with low beam sizes of H6054, H4703, and 9006 for the front lighting assembly. A replacement chart documents bulb size data spanning 1987 to 1991 model years.

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
1988-1991	H6054 (With 2 Rectangular Headlamps)
	H4701 (With 4 Rectangular Headlamps)
	9005 (With Halogen Capsule Headlamps)
1987	H6054 (With 2 Headlamps)
1987	H4651 (With 4 Headlamps)

Low Beam Headlight

Years	Bulb Size
1988-1991	H6054 (With 2 Rectangular Headlamps)
	H4703 (With 4 Rectangular Headlamps)
	9006 (With Halogen Capsule Headlamps)
1987	H6054 (With 2 Headlamps)
1987	H4652 (With 4 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, variant. Not a replaceable bulb — the entire unit is replaced. 12V.	H4701
ANSI standard (US & Canada). Single-filament halogen bulb with P20d base. 12V, 65W.	9005
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). 7-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4703
ANSI standard (US & Canada). Single-filament halogen bulb with P22d base. 12V, 55W.	9006
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit, variant of H4651. Not a replaceable bulb — the entire unit is replaced. 12V.	H4652

Other Locations

Additional Notes

The GMC R3500 headlight specifications span the 1987-1991 model years and cover three distinct headlamp system configurations: a 2-lamp rectangular setup, a 4-lamp rectangular setup, and a halogen capsule system. Each configuration requires different bulb types for both high and low beam functions.
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 and low beam bulb in the 2-rectangular-headlamp configuration across the 1988-1991 model years, meaning a single sealed unit handles both functions rather than separate high and low beam bulbs.
Sealed beam units such as the H6054, H4701, H4703, H4651, and H4652 are not bulbs in the conventional sense. The entire lens, reflector, and filament assembly is replaced as one unit when the light fails, unlike modern halogen capsule bulbs where only the internal bulb is swapped out.
The 4-lamp rectangular configuration on the 1987 R3500 uses the H4651 for high beam and the H4652 for low beam. The H4652 is a variant of the H4651, both being 4x6-inch rectangular sealed beam units at 12V. These differ from the H4701 and H4703 used in the same 4-lamp position for 1988-1991, which are 7-inch round sealed beam units.
The halogen capsule headlamp configuration, available on the 1988-1991 R3500, uses the 9005 for high beam and the 9006 for low beam. Both are single-filament ANSI-standard halogen bulbs operating at 12V, with the 9005 rated at 65W and the 9006 rated at 55W.
The 9005 and 9006 differ in their base types: the 9005 uses a P20d base while the 9006 uses a P22d base. These bases are physically incompatible with each other, meaning the high and low beam positions in a halogen capsule system cannot accept the same bulb.
The H4701 and H4703 are both 7-inch round sealed beam units used in the 4-rectangular-headlamp configuration for 1988-1991, with H4701 designated for high beam and H4703 for low beam. Though similar in form, they are distinct part numbers and are not interchangeable between beam positions.
All bulb types listed across the R3500 specifications conform to ANSI standards applicable in both the US and Canada, and all operate on a 12V electrical system regardless of headlamp configuration or model year.