International S1854 front turn signal bulbs use 1156 size while rear turn signal bulbs use 1157 size. The replacement chart covers vehicle production from 1981 to 1989 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 S1854 uses the 1156 bulb for the front turn signal across all documented model years from 1981-1989.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and recognized under ANSI standards in both 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 International S1854 uses the 1157 bulb for the rear turn signal across all documented model years from 1981-1989.
The 1157 is a dual-filament bulb rated at 12V with a 21W high filament and a 5W low filament, fitted with a BAY15d bayonet base, and also recognized under ANSI standards in both the United States and Canada.
The BAY15d base features two contacts offset at different heights to prevent incorrect installation, a design that differs from the single-contact BA15s base used by the 1156.
Because the 1156 and 1157 share a similar physical profile but carry different base types and filament configurations, the two bulbs are not interchangeable with one another.
The dual-filament design of the 1157 allows the rear turn signal housing to serve a secondary lighting function through the lower-wattage filament, a capability the single-filament 1156 does not provide.