The Peterbilt 357 front and rear turn signal bulbs utilize a 2057 or 198 size, with both locations sharing identical bulb specifications. The replacement chart covers vehicle production spanning 1986 to 2008.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 2057 is the dominant bulb type across the Peterbilt 357 turn signal specifications, appearing in both front and rear positions across nearly the entire 1986-2008 model range.
The 2057 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with filaments drawing 26.9W and 8W respectively, making it suitable for combined stop and turn signal functions.
The 2057 is a brighter variant of the 1157, sharing the same BAY15d base, which means the two types are physically similar but not electrically identical and should not be treated as direct substitutes without confirming wattage compatibility.
The 198 is a miniature wedge bulb of the T5 type, rated at 12V and 2W, representing a significantly lower power draw than the 2057 and serving a different circuit role within the same vehicle platform.
Both the 2057 and 198 conform to ANSI standards recognized in the United States and Canada, placing them within a standardized North American bulb classification system.
On the Peterbilt 357, the 198 bulb is associated with specific headlamp configurations, including halogen capsule headlamps and, in certain model years, four rectangular headlamp setups, indicating that the front turn signal bulb selection is tied to the headlamp assembly type rather than the model year alone.
The rear turn signal on the 1991 Peterbilt 357 uses the 2057 specifically with the four round headlamp configuration, while the 198 applies to other configurations that year, reinforcing that headlamp type is a determining factor for bulb selection across both front and rear positions.
Several model years carry two separate bulb listings for the same position, such as 1992 and 1994, where both the 2057 and 198 are listed with differing headlamp conditions, meaning the correct bulb cannot be determined from the model year alone without knowing the installed headlamp type.
The year 1996 lists the 198 as the sole front and rear turn signal bulb with no headlamp condition qualifier, distinguishing it from surrounding years where the 2057 is the standard fitment.
Because the 2057 and 198 differ in base type, wattage, and filament count, they are not interchangeable, and installing the incorrect type for a given headlamp configuration would result in a fitment or electrical mismatch.