International S1925 front turn signal bulbs measure 1156 in size, while rear turn signal bulbs measure 1157 in size. The replacement chart covers vehicle production spanning 1980 to 1982 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The International S1925 uses the 1156 bulb for the front turn signal across the 1980-1982 model years.
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 S1925 uses the 1157 bulb across the same 1980-1982 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 incorrect installation of single-contact bulbs in dual-filament sockets.
Although both the 1156 and 1157 share a 12V operating voltage and a 21W primary wattage, their base types differ, making them non-interchangeable despite their similar appearance.
The dual-filament design of the 1157 allows it to serve both turn signal and running light functions simultaneously through its two separate filaments.
Both the 1156 and 1157 conform to ANSI standards applicable in the United States and Canada, indicating standardized dimensional and electrical specifications across manufacturers.