Kenworth K150 high beam headlight bulbs use H4651 size while low beam headlight bulbs use H4656 or H4652 size. The replacement chart covers 1990 to 1994 vehicle production years 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 K150 uses H4651 sealed beam units for the high beam headlight position across all listed model years, 1990-1994, with no variation in that position throughout the range.
The H4651, H4652, and H4656 are all ANSI-standardized 4x6-inch rectangular sealed beam units rated at 12V, meaning the entire housing is replaced as a single unit rather than containing a separate replaceable bulb inside.
The H4652 is a variant of the H4651, sharing the same sealed beam format and ANSI classification while being a distinct part number used in the low beam position.
The low beam headlight position on the Kenworth K150 uses the H4656 for 1990-1992 and 1994, while the 1993 model year uses the H4652 instead, making 1993 the only year in the listed range with a differing low beam specification.
Because the H4651 and H4652 are related variants and the H4656 is a separate type, substituting one for another without confirming ANSI compatibility could result in incorrect fitment, as each part number corresponds to a specific beam pattern and connector configuration within the sealed beam standard.
The ANSI standardization of all three bulb types means they conform to a shared physical and electrical specification recognized across the United States and Canada, which governs the mounting interface and output characteristics of each unit.