GMC R2500 Suburban Headlight Bulb Size

The GMC R2500 Suburban headlight bulb specifications include high beam sizes H6054, H4701, and H4651, along with low beam sizes H6054, H4703, and H4656 in various bulb configurations. The replacement chart covers 1987 to 1991 production years with corresponding bulb size data.

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
1989-1991	H6054 (With 2 Headlamps)
1989-1991	H4701 (With 4 Headlamps)
1987-1988	H6054 (With 2 Headlamps)
1987-1988	H4651 (With 4 Headlamps)

Low Beam Headlight

Years	Bulb Size
1989-1991	H6054 (With 2 Headlamps)
1989-1991	H4703 (With 4 Headlamps)
1987-1988	H6054 (With 2 Headlamps)
1987-1988	H4656 (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). 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). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656

Other Locations

Additional Notes

The GMC R2500 Suburban uses sealed beam headlight units across all listed model years (1987-1991), meaning the entire housing and lens assembly is replaced as a single unit rather than swapping an internal bulb.
All five bulb types found in these specifications, the H6054, H4701, H4651, H4703, and H4656, operate on 12V and conform to ANSI standards recognized in both the United States and Canada.
The H6054 is a 5x7-inch rectangular sealed beam unit that serves as both the high beam and low beam in two-headlamp configurations, covering all model years listed from 1987 through 1991.
In four-headlamp configurations, the high beam and low beam functions are handled by separate sealed beam units, which is why distinct part numbers appear for each function depending on the model year.
The GMC R2500 Suburban (1989-1991) with four headlamps uses the H4701 for high beam and the H4703 for low beam, both of which are 7-inch round sealed beam units of different variants.
For the 1987-1988 model years with four headlamps, the high beam uses the H4651 and the low beam uses the H4656, both of which are 4x6-inch rectangular sealed beam units designated for their respective functions.
The H4701 and H4703 are not interchangeable despite both being 7-inch round units, as each is rated and designated specifically for either high beam or low beam output.
Similarly, the H4651 and H4656 share the same 4x6-inch rectangular form but are not interchangeable, as each unit is engineered for a distinct beam function within the four-headlamp system.