The Lincoln Mark LT uses a 3157NA bulb size for front turn signals and a 3457 bulb size for rear turn signals. The replacement chart covers 2006 to 2008 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 Lincoln Mark LT uses the 3157NA bulb for the front turn signal across the 2006-2008 model years.
The 3157NA is a dual-filament T25 wedge bulb rated at 12V with a 27W/7W output, where the higher wattage filament serves the turn signal function and the lower wattage filament serves a secondary lighting function such as parking or running light duty.
The natural amber glass of the 3157NA produces a yellow-orange light output directly from the bulb itself, without relying on a colored lens to achieve the amber turn signal appearance.
The rear turn signal on the Lincoln Mark LT (2006-2008) uses the 3457 bulb, which shares the same T25 wedge base and 12V, 27W/7W dual-filament configuration as the 3157NA.
The 3457 differs from the 3157NA in that it lacks the natural amber glass coating, meaning its light output is clear rather than pre-tinted amber.
Both the 3157NA and 3457 conform to ANSI standards applicable in the United States and Canada, indicating standardized electrical and photometric performance requirements.
Although the 3157NA and 3457 share the same T25 wedge base and wattage ratings, the difference in glass tinting means the two bulbs are not functionally interchangeable in all applications without affecting the color output at the lens.