Kenworth T800 Headlight Bulb Size

Additional Notes

• The H4651 sealed beam unit is the most consistently specified high beam bulb across the Kenworth T800, covering model years 1987-1997 as well as 2003-2004 configurations equipped with four rectangular headlamps. As a sealed beam unit, the lens, reflector, and filament are fused into a single assembly, meaning the entire unit is replaced rather than an internal bulb.
• The 4x6-inch rectangular sealed beam format is shared by three distinct bulb types in these specifications: H4651, H4652, and H4656. Although all three share the same physical housing format and 12V rating, they are separate ANSI-designated units and are not interchangeable across positions or model years without confirming the exact fitment requirement.
• The H4652 is specified as a variant of the H4651 and is designated exclusively for low beam positions. The H4651 itself appears only in high beam positions, making the two units position-specific despite their shared physical format.
• The H6054 is a 5x7-inch rectangular sealed beam unit rated at 12V and is specified for both high and low beam positions on 2003-2004 T800 models equipped with two rectangular headlamps. Like the 4x6-inch units, it is a non-serviceable assembly replaced as a whole.
• The 9004 is the only replaceable halogen bulb type in these specifications. It uses a P29t base, operates at 12V, and carries a dual-filament design rated at 65W for high beam and 45W for low beam, allowing a single bulb to serve both functions within a halogen capsule headlamp system.
• For 2003-2004 Kenworth T800 models, the correct bulb type is determined by the headlamp configuration installed on the vehicle. Three distinct configurations are listed: two rectangular headlamps, four rectangular headlamps, and halogen capsule headlamps, each requiring a different bulb type for both high and low beam positions.
• The low beam fitment for four-rectangular-headlamp configurations shows variation across model years. The 2004 specification lists H4656, while the 2003 specification lists H4652 for the same configuration, indicating that the two units are not assumed to be interchangeable between those years.
• All bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada, and all operate on a 12V electrical system, consistent with standard commercial vehicle electrical architecture.