Kenworth K100E headlight bulbs utilize H4651 size for high beam and H4656 or H4652 sizes for low beam applications. The replacement chart covers 1985 through 1997 model year data with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Kenworth K100E uses H4651, H4656, and H4652 bulb types across its headlight positions, all of which are ANSI-standardized sealed beam units operating at 12V and sharing a 4x6-inch rectangular form factor.
Sealed beam units, by design, do not contain a replaceable internal filament. When a sealed beam fails, the entire unit is replaced as a single assembly.
The H4651 serves as the high beam headlight across all documented model years, 1985-1997, without variation.
The H4652 is specified as a variant of the H4651, meaning it shares the same 4x6-inch rectangular sealed beam construction while differing in its beam pattern, which is optimized for low beam output.
The low beam position on the Kenworth K100E is not uniform across all years. Model years 1991-1993 and 1989 use the H4652, while 1985-1988, 1990, and 1994-1997 use the H4656.
The H4651, H4652, and H4656 all conform to ANSI standards recognized in both the United States and Canada, placing them within a standardized interchangeability framework by physical size, though beam pattern differences between types make them functionally non-interchangeable between high and low beam positions.