Ford Excursion front turn signal bulbs use 3157NA or 3157 size, while rear turn signal bulbs use 3457 size. The replacement chart covers 2000 to 2005 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford Excursion uses two bulb types across its front and rear turn signal positions: the 3157 family for the front and the 3457 for the rear, with both belonging to the T25 wedge form factor and sharing identical electrical ratings of 12V, 27W/7W.
The dual-filament design of both the 3157 and 3457 bulbs means each unit carries two separate filaments within a single housing, allowing one circuit to handle a high-wattage function and another to handle a low-wattage function from the same socket.
All three bulb types listed in the specifications, the 3157NA, 3157, and 3457, conform to ANSI standards recognized in both the United States and Canada.
The 3157NA used in the 2005 Ford Excursion front turn signal position is distinguished from the standard 3157 by its natural amber glass envelope, which produces an amber output without relying on the vehicle's lens to filter the light color.
The 2000-2004 front turn signal positions use the 3157, which has a clear glass envelope, whereas the 2005 model year shifts to the 3157NA with its amber glass, making these two bulbs non-identical despite sharing the same T25 base and electrical ratings.
The 3457 and 3157 share the same T25 wedge base and the same 12V, 27W/7W ratings, but they carry different ANSI part numbers, which indicates a distinction in their internal construction or contact configuration that affects direct interchangeability.
The rear turn signal position on the Ford Excursion uses the 3457 consistently across all model years from 2000-2005, without variation.
The 27W filament in these dual-filament bulbs corresponds to the higher-draw circuit, typically associated with the active turn signal flash, while the 7W filament serves the lower-draw circuit, commonly associated with a parking or running light function.