The Freightliner M2 front turn signal uses a 3157NA bulb size while the rear turn signal requires a 1157 bulb size. The replacement chart covers vehicle production spanning from 2002 through 2024 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 Freightliner M2 uses the 3157NA for the front turn signal across all listed model years from 2002-2024. This bulb is a dual-filament T25 wedge type rated at 12V with a 27W high filament and a 7W low filament. The "NA" suffix denotes natural amber glass, meaning the color is built into the bulb itself rather than produced by a colored lens.
The 1157 serves as the rear turn signal bulb across the same 2002-2024 model year span. It operates on a BAY15d bayonet base, which uses two offset pins at different heights to prevent incorrect installation. Its dual-filament design runs at 12V with a 21W high filament and a 5W low filament.
Both the 3157NA and 1157 conform to ANSI standards recognized in the United States and Canada, placing them within a standardized sizing and performance framework shared across many North American vehicle applications.
Although both bulbs are dual-filament types operating at 12V, the 3157NA and 1157 are not interchangeable. They differ in base type, wattage ratings, and physical form factor, with the 3157NA using a wedge base and the 1157 using a bayonet base.
The higher wattage filament on the 3157NA (27W) exceeds that of the 1157 (21W), meaning the front turn signal produces a brighter output at full intensity than the rear unit under equivalent voltage conditions.
The natural amber glass of the 3157NA is a functional specification, not merely cosmetic. It produces the amber signal color independently of the housing lens, which is relevant when the front housing uses a clear or non-amber lens.
The 1157's BAY15d base is a widely used standard in automotive rear lighting, and direct-fit LED replacements in this base type are broadly available, though any substitute must match the original wattage draw or account for load resistor requirements to avoid hyperflash in the turn signal circuit.
The consistency of both bulb sizes across all 23 listed model years of the Freightliner M2 indicates that the front and rear turn signal housings share the same socket specifications throughout the entire production range covered by these data.