Kenworth T400 Headlight Bulb Size

Kenworth T400 headlight bulbs utilize H4651 and H5001 sizes for high beam applications and H4652, H4656, and H5006 sizes for low beam functions, with each bulb size corresponding to specific lighting requirements. The replacement chart covers 1982 through 1997 model years and details the bulb specifications across the vehicle's production span.

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
1989-1997	H4651	Check Price
1984	H4651	Check Price
1982	H5001	Check Price

Low Beam Headlight

Years	Bulb Type	Shop
1993-1997	H4652	Check Price
1990-1992	H4656	Check Price
1989	H4652	Check Price
1984	H4652	Check Price
1982	H5006	Check Price

Bulb Specifications

Description	Type	Shop
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). 4-inch square sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5001	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit, variant of H4651. Not a replaceable bulb — the entire unit is replaced. 12V.	H4652	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
ANSI standard (US & Canada). 5.75-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5006	Check Price

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Additional Notes

The H4651 and H4652 are the most frequently specified bulb types across the Kenworth T400 headlight data, with H4651 covering high beam and H4652 covering low beam for the majority of model years listed.
Both the H4651 and H4652 are ANSI-standard 4x6-inch rectangular sealed beam units operating at 12V. The H4652 is formally classified as a variant of the H4651, differentiated by its low beam light distribution pattern rather than its physical housing.
All sealed beam types listed in these specifications, including the H4651, H4652, H4656, H5001, and H5006, are whole-unit replacements. The light source is not a separate, serviceable component inside the housing.
The Kenworth T400 (1982) is the only model year specifying the H5001 for high beam and the H5006 for low beam. The H5001 is a 4-inch square sealed beam unit, and the H5006 is a 5.75-inch round sealed beam unit, both at 12V, making the 1982 fitment physically distinct from all other years listed.
The H4656 is specified for low beam on the 1989-1992 model years, while surrounding years use the H4652 instead. Although both are 4x6-inch rectangular sealed beam units, they are not the same part number and are not listed as interchangeable within these specifications.
All bulb types across the full range of T400 years listed operate at 12V, placing them within the standard automotive and commercial vehicle electrical system voltage.
The ANSI standardization of these sealed beam types means the physical housing conforms to defined size and mounting specifications shared across multiple vehicle manufacturers, though beam pattern and part number differences still affect direct substitution.
For the high beam position, the T400 used the H4651 consistently from 1984 through 1997, with the sole exception being the H5001 specified for 1982.