The Ford F-600 Super Duty uses 7444NA bulb size for front turn signals and 4257NA bulb size for rear turn signals. The replacement chart covers 2020 through 2022 vehicle production 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 F-600 Super Duty uses two distinct dual-filament wedge bulb types across its front and rear turn signal positions.
The 7444NA is an ANSI-standardized bulb for the US and Canadian markets, built to a T20 wedge form factor with natural amber glass and rated at 12V with a 21W/5W dual-filament output.
The dual-filament design of the 7444NA allows it to serve two lighting functions simultaneously, with the 21W filament handling the higher-intensity turn signal function and the 5W filament serving a lower-intensity role such as a parking or running light.
The natural amber glass of the 7444NA produces an amber signal output without relying on a colored lens, which is a characteristic of the NA designation in the bulb naming convention.
The 4257NA is also an ANSI-standardized dual-filament wedge bulb with natural amber glass, rated at 12V and sharing the NA designation with the 7444NA.
The front turn signal positions on the Ford F-600 Super Duty use the 7444NA for the 2021-2022 model years.
The rear turn signal positions use the 4257NA for the 2020-2022 model years.
The 7444NA and 4257NA are not interchangeable, as they differ in wattage ratings and physical form factor specifications, meaning each is specific to its designated position.
Both bulb types carry ANSI standardization, which indicates they conform to defined electrical and physical tolerances recognized across the US and Canadian markets.
The wedge base construction on both bulb types means they are secured by the socket itself rather than by a separate metal base with pins, which is a common trait in modern automotive lighting applications.