International S2375 front turn signal bulbs use 1156 size while rear turn signal bulbs use 1157 size. The replacement chart covers 1984 to 1988 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 S2375 uses the 1156 bulb for the front turn signal across the 1984-1988 model years covered in the specifications.
The 1156 is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The BA15s base designation indicates a single-contact bayonet mount, which is not interchangeable with dual-contact bayonet bases.
The rear turn signal on the International S2375 uses the 1157 bulb across the same 1984-1988 model years.
The 1157 is an ANSI-standard dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, fitted with a BAY15d bayonet base.
The BAY15d base features offset locating pins, which physically prevents the 1157 from being seated in a socket designed for the BA15s base used by the 1156.
Although both the 1156 and 1157 share the same 12V operating voltage and a 21W filament, the difference in base type and filament count makes them non-interchangeable between front and rear positions.
Both the 1156 and 1157 are ANSI standards recognized in the United States and Canada, indicating broad availability across North American markets.