The Freightliner 108SD front turn signal requires a 3457NA bulb size while the rear turn signal uses a 1157 bulb size. Replacement specifications covering 2012 to 2017 production years are detailed in the chart.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Freightliner 108SD uses the 3457NA bulb for the front turn signal across all 2012-2017 model years. This is a dual-filament T25 wedge bulb rated at 12V with a 27W high filament and 7W low filament, constructed with natural amber glass.
The natural amber glass of the 3457NA produces an amber output without relying on a colored lens, which is a design characteristic of the NA suffix designation in ANSI bulb nomenclature.
The rear turn signal on the 108SD uses the 1157 bulb across all 2012-2017 model years. It is a dual-filament bulb rated at 12V with a 21W high filament and 5W low filament.
The 1157 uses a BAY15d bayonet base, which features two offset pins at different heights. This offset pin configuration prevents incorrect installation by ensuring the bulb seats only in one orientation.
Both the 3457NA and 1157 are ANSI-standardized bulbs recognized in the US and Canada, meaning physical and electrical specifications are consistent across manufacturers producing these part numbers.
The front and rear turn signal bulbs on the 108SD are not interchangeable. The 3457NA uses a wedge base while the 1157 uses a BAY15d bayonet base, and their wattage ratings also differ between positions.