International S1954 front turn signal bulbs use 1156 size while rear turn signal bulbs use 1157 size. The replacement chart covers vehicle production spanning 1981 to 1990.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The International S1954 uses the 1156 bulb for the front turn signal across all listed model years from 1981-1990.
The 1156 is a single-filament bulb operating at 12V and 21W, fitted with a BA15s bayonet base, and is standardized under ANSI specifications for use in the United States and Canada.
The BA15s base designation indicates a single-contact bayonet fitting with a 15mm base width, which is not interchangeable with dual-contact bayonet bases.
The rear turn signal on the International S1954 uses the 1157 bulb across all listed model years from 1981-1990.
The 1157 is a dual-filament bulb rated at 12V with two wattage outputs, 21W for the high-intensity filament and 5W for the low-intensity filament, allowing it to serve both turn signal and running light functions from a single socket.
The 1157 uses a BAY15d bayonet base, which features offset pins to prevent incorrect installation. This base is physically distinct from the BA15s base used by the 1156, making the two bulbs non-interchangeable.
Both the 1156 and 1157 are ANSI-standardized bulbs, meaning their electrical and physical specifications conform to a defined industry standard across manufacturers in the United States and Canada.
The front and rear turn signal positions on the International S1954 require different bulb types, with the single-filament 1156 at the front and the dual-filament 1157 at the rear.