The International 5600i front turn signal uses a 3157NA bulb size while the rear turn signal requires a 1157 bulb size. The replacement chart covers 2011 through 2014 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 International 5600i uses two distinct bulb types across its front and rear turn signal positions for the 2011-2014 model years: the 3157NA at the front and the 1157 at the rear.
The 3157NA is a dual-filament T25 wedge bulb rated at 12V with a 27W high filament and a 7W low filament, meaning it serves both a bright signaling function and a reduced-intensity parking or running light function within a single housing.
The "NA" designation in the 3157NA indicates natural amber glass, which produces an amber output from the bulb itself rather than relying on a colored lens to filter a clear light source.
The 1157 is a dual-filament bulb rated at 12V with a 21W high filament and a 5W low filament, and it uses a BAY15d bayonet base, which features two offset pins to ensure correct orientation during installation.
Both the 3157NA and the 1157 conform to ANSI standards applicable in the United States and Canada, indicating standardized electrical and photometric performance across compliant products.
The 3157NA and the standard 3157 share the same base and filament configuration, but the natural amber glass of the 3157NA makes it non-interchangeable in applications where the lens is clear and amber output is required by design.
The 1157 and the 2057 bulb share the BAY15d bayonet base, but they differ in filament wattage ratings, which can affect compatibility in circuits calibrated for a specific load.
Because the front and rear positions use physically different base types, a wedge-base 3157NA cannot be installed in a rear socket designed for the bayonet-base 1157, and vice versa.