Peterbilt 348 front turn signal bulbs use 3157NA size while rear turn signal bulbs use 1157 size. Replacement chart data covers 2010 through 2017 vehicle production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Peterbilt 348 uses two distinct bulb types across its turn signal positions for model years 2010-2017: the 3157NA at the front and the 1157 at the rear.
Both the 3157NA and 1157 are ANSI-standardized bulbs rated for use in the United States and Canada, and both operate on a 12-volt electrical system.
Both bulb types feature dual-filament construction, which allows a single bulb to serve two brightness levels within the same housing, typically one filament for running light function and one for the higher-intensity signal flash.
The 3157NA, used in the front turn signal position of the Peterbilt 348, carries a 27W/7W power rating, with the higher wattage filament handling the active signal function.
The "NA" suffix in the 3157NA designation indicates natural amber glass, meaning the bulb itself produces an amber-tinted output rather than relying on a colored lens to achieve the required signal color.
The 3157NA is a T25 wedge-type bulb, which uses a wedge base rather than a metal pin base, and is seated directly into a compatible socket without a separate locking mechanism.
The 1157, used in the rear turn signal position, carries a 21W/5W power rating and uses a BAY15d bayonet base, which features two offset pins that lock the bulb into its socket upon a partial rotation.
The 3157NA and 1157 are not interchangeable with each other, as they differ in base type, wattage, and glass construction, making position-specific installation a relevant fitment consideration.
The BAY15d base of the 1157 is a widely used standard in automotive rear lighting, though correct wattage and filament orientation should be confirmed before substitution with any alternative bulb carrying the same base type.
The natural amber glass of the 3157NA distinguishes it from the clear-glass 3157, and substituting a clear variant in the front turn signal position of the Peterbilt 348 may affect compliance with signal color regulations depending on the lens housing used.