The Peterbilt 359 front and rear turn signal bulbs utilize 198 and 2057 sizes, with both bulb sizes applicable to each location. The replacement chart covers vehicle production spanning 1986 to 1988, detailing bulb size specifications across those years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Peterbilt 359 front turn signal uses two different bulb types across the 1986-1988 model years: the 198 and the 2057, with fitment determined by headlamp configuration.
The 2057 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 26.9W/8W output, where the higher wattage filament serves the turn signal function and the lower wattage filament serves a secondary function such as running light duty.
The 198 is a miniature wedge bulb of the T5 type, rated at 12V and 2W, and conforms to ANSI standards applicable in both the United States and Canada.
On the 1987-1988 Peterbilt 359, the front turn signal position requires the 198 bulb only under specific headlamp configurations, making the headlamp type a critical factor in determining the correct front turn signal bulb.
The 1988 Peterbilt 359 front turn signal takes the 198 bulb when equipped with four rectangular headlamps, while the 2057 applies to the standard configuration without that designation.
The 1987 Peterbilt 359 front turn signal takes the 198 bulb when equipped with four round headlamps, a distinction that separates it from the 1988 rectangular headlamp condition.
The 2057 is described as a brighter variant of the 1157 bulb. Despite their physical and electrical similarities, these two bulbs are not confirmed as interchangeable within these specifications.
The rear turn signal on the 1987 Peterbilt 359 lists the 198 bulb specifically for vehicles with halogen capsule headlamps, indicating that headlamp type influences rear turn signal fitment as well as front.
The 2057 is the rear turn signal bulb for the 1986-1988 Peterbilt 359 across all configurations not otherwise specified by a headlamp condition.
Both the 198 and 2057 conform to ANSI standards recognized in the United States and Canada, placing them within a standardized classification system used to define bulb base type, voltage, and wattage.