Freightliner Argosy Turn Signal Bulb Size

The Freightliner Argosy front turn signal bulb uses 5702AK or 4157NA size specifications. The replacement chart covers vehicle production years 2005 through 2007.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Front Turn Signal

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
2007	5702AK	5702AK	Check Price
2005-2006	4157NA	PY27/7W	Check Price

Bulb Specifications

Description	Type	Shop
Sylvania part number for a coated variant of the ANSI 3157 bulb. Dual-filament wedge bulb (T25), amber coating. 12V, 27W/7W.	5702AK	Check Price
ANSI standard (US & Canada). Dual-filament wedge bulb (T25), natural amber glass. 12V, 27W/7W.	4157NA	Check Price

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Additional Notes

The Freightliner Argosy front turn signal specifications cover the 2005-2007 model years, with two distinct bulb types listed across that range.
The 4157NA is the bulb type specified for the 2005-2006 model years. It is an ANSI-standardized dual-filament wedge bulb in the T25 form factor, rated at 12V with a 27W main filament and a 7W secondary filament, and it produces its amber output through natural amber glass rather than a coating.
The 5702AK is specified for the 2007 model year. It is a Sylvania part number designating a coated variant of the ANSI 3157 bulb, sharing the same T25 wedge form factor and 12V, 27W/7W electrical ratings as the 4157NA, but achieving its amber output through an applied coating over clear glass rather than through the glass itself.
Although the 4157NA and 5702AK share the same T25 wedge base, voltage, and wattage ratings, they are not the same part. The 4157NA is an ANSI-standardized type recognized across the US and Canadian markets, while the 5702AK is a manufacturer-specific part number tied to Sylvania.
The dual-filament design present in both bulb types means each bulb serves two functions within a single housing, with the higher-wattage filament (27W) typically handling the turn signal flash and the lower-wattage filament (7W) handling a secondary function such as parking or running light duty.
The amber color output method differs between the two specified bulbs. Natural amber glass, as used in the 4157NA, is inherent to the glass envelope itself, while the amber coating on the 5702AK is an external application. This distinction can affect light transmission characteristics even when wattage ratings are identical.