International S1924 front turn signal bulbs use 1156 size while rear turn signal bulbs use 1157 size. The replacement chart covers 1980 to 1982 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 S1924 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.
A BA15s base has a single contact pin, which physically prevents substitution with dual-filament bulbs that use a different base configuration.
The International S1924 uses the 1157 bulb for the rear turn signal across the 1980-1982 model years.
The 1157 is an ANSI-standard dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, fitted with a BAY15d bayonet base.
The BAY15d base features two offset contact pins, a design that prevents incorrect installation of single-filament bulbs in sockets intended for dual-filament use.
The dual-filament design of the 1157 allows the rear position to serve two electrical functions, with the lower-wattage filament typically handling a steady running or parking light function alongside the higher-wattage turn signal filament.
Although both the 1156 and 1157 share a 12V operating voltage and a 21W primary wattage rating, their base types are not interchangeable due to the differing pin configurations of the BA15s and BAY15d sockets.