Kenworth T600A front and rear side marker bulbs utilize 1157, 904, and 67 bulb sizes depending on location and production specifications. The replacement chart covers 1986 through 1997 vehicle 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.
The Kenworth T600A front side marker uses three distinct bulb types across its model years: the 1157, 904, and 67, with the 1157 being the most frequently specified, covering model years 1989-1997 with the exception of 1987 and 1988.
The 1157 is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. Its dual-filament design distinguishes it from the single-filament bulbs also present in these specifications.
The 904 is a miniature wedge bulb in the T10 form factor, rated at 12V and 8W. Its wedge base differs fundamentally from the bayonet bases used by the 1157 and 67, meaning it is not physically interchangeable with either of those types without a socket adapter or housing modification.
The 67 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 8W. It is considered a lower wattage variant of the 1156 bulb family and shares the same base type as the 1156, though the two are not equivalent in wattage output.
The rear side marker of the Kenworth T600A relies most heavily on the 904 bulb, which is specified for model years 1986-1992 and 1995-1997, with the 67 appearing in 1988, 1993, and 1994.
The front and rear side markers do not consistently use the same bulb type within the same model year. For example, the 1989-1992 model years specify a 1157 for the front position while the rear uses a 904, indicating that the two positions require separate bulb purchases.
The 1157 does not appear in the rear side marker specifications at any point, while it is the dominant bulb in the front side marker position. Substituting a 1157 for a 904 or 67 in the rear position would involve a mismatch in both base type and wattage.
All three bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada, indicating a standardized electrical rating system governs their classification rather than a proprietary one.
The 1987 front side marker is the only instance across both positions where the 67 bulb is specified in isolation for that position, as all surrounding years in the front marker use either the 1157 or 904.
Because the 904 uses a wedge base and the 67 uses a BA15s bayonet base, these two bulbs occupy different socket types despite sharing the same 12V, 8W electrical rating, and one cannot serve as a direct drop-in replacement for the other.