The Kenworth K100 high beam headlight bulb size includes H4651 and H5001 options, while low beam headlight bulb size encompasses H4656, H4652, and H5006 specifications. The replacement chart covers 1981 to 1985 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.
All headlight bulb types specified for the Kenworth K100 across 1981-1985 are sealed beam units, meaning the entire lens-reflector-filament assembly is replaced as one piece rather than swapping an individual bulb.
The H4651 and H4656 are both 4x6-inch rectangular sealed beam units operating at 12V and conforming to ANSI standards recognized in the United States and Canada. The H4651 serves the high beam position, while the H4656 serves the low beam position, making them non-interchangeable despite sharing the same physical form factor.
The H4652, used in the 1984 low beam position, is a variant of the H4651 in a 4x6-inch rectangular sealed beam format. Although it shares the same physical shape as the H4651, the two carry different ANSI designations and are not interchangeable between beam positions.
The H5001, used in the high beam position for 1981-1983, is a 4-inch square sealed beam unit operating at 12V. Its square form factor is physically distinct from the rectangular H4651 used in 1984-1985, reflecting a change in headlight housing design between those model years.
The H5006, used in the low beam position for 1981-1983, is a 5.75-inch round sealed beam unit operating at 12V. This round format differs from all other headlight types listed for the K100, and it is paired exclusively with the square H5001 high beam unit during those years.
The 1985 model year is the only year in which the high beam and low beam headlights share the same 4x6-inch rectangular sealed beam format under different ANSI designations, with the H4651 for high beam and the H4656 for low beam.
All five bulb types across the specifications conform to ANSI standards applicable in both the United States and Canada, indicating regulatory compliance across both markets for the listed model years.