The International 5900i front turn signal uses a 3157NA bulb size while the rear turn signal requires a 1157 bulb size. The replacement chart covers 2011 to 2012 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 5900i uses two distinct bulb types across its front and rear turn signal positions for the 2011-2012 model years: the 3157NA at the front and the 1157 at the rear.
Both the 3157NA and 1157 are ANSI-standardized bulbs recognized in the United States and Canada, meaning they conform to defined electrical and physical specifications rather than proprietary formats.
Both bulb types operate on a 12-volt system and feature dual-filament construction, where one filament handles the higher-wattage turn signal function and the other handles a lower-wattage parking or running light function.
The 3157NA, used at the front turn signal position, carries a 27W/7W wattage rating, with the higher filament dedicated to the active signal and the lower filament to the secondary lighting function.
The 1157, used at the rear turn signal position, carries a 21W/5W wattage rating, making it a lower-output bulb than the 3157NA across both filaments.
The 3157NA uses a T25 wedge base, which is a plastic wedge-style fitting that seats directly into a compatible socket without a metal base collar.
The 1157 uses a BAY15d bayonet base, a two-pin offset bayonet mount that locks into its socket with a twist. The offset pin spacing prevents incorrect filament orientation during installation.
The "NA" suffix in the 3157NA designation indicates natural amber glass, meaning the amber color is produced by the glass envelope itself rather than by a coated or painted lens. This distinguishes it from the clear-glass 3157 variant.
Because the 3157NA and 1157 use physically incompatible base types, a wedge-base and a bayonet-base respectively, the two bulbs are not interchangeable between the front and rear positions of the International 5900i.