The Kenworth K100 front side marker uses bulb sizes 67, 1157, or 904, while the rear side marker uses 67 or 1157. The replacement chart covers 1981 to 1985 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 K100 side marker specifications cover model years 1981-1985, with three distinct bulb types appearing across the front and rear positions: the 67, 1157, and 904.
The 67 bulb is the most frequently specified type across both the front and rear side marker positions of the K100, appearing in six of the ten total position-year entries.
The 67 is a single-filament bulb rated at 12V and 8W, fitted with a BA15s bayonet base. It conforms to ANSI standards recognized in both the United States and Canada.
The 1157 bulb carries a dual-filament design rated at 12V with a split wattage of 21W and 5W, and uses a BAY15d bayonet base. Its dual-filament construction distinguishes it electrically from the single-filament 67.
The BA15s base of the 67 and the BAY15d base of the 1157 are not interchangeable. The BAY15d base features offset locating pins to prevent incorrect installation, while the BA15s base does not, making physical substitution between these two types unreliable without verification.
The 904 is a miniature wedge bulb of the T10 type, rated at 12V and 8W. Its wedge base differs fundamentally from the bayonet bases used by both the 67 and the 1157, making it incompatible with sockets designed for either of those types.
The front side marker position of the Kenworth K100 used three different bulb types across the 1981-1985 span, with the 904 specified exclusively for the 1981 model year in that position.
The rear side marker position used only the 67 and 1157 types, with the 1157 appearing solely in the 1983 model year for that position.
The 1157 and 67 share the same 12V operating voltage but differ substantially in wattage and filament count, meaning a 67 installed in a socket specified for a 1157 would not replicate the dual-filament behavior the circuit may require.
Although the 67 and 904 share the same 12V, 8W electrical rating, their base types are physically distinct, and one cannot serve as a direct replacement for the other without a compatible socket.