International S1823 front turn signal bulbs measure 1156 in size, while rear turn signal bulbs measure 1157 in size. The replacement chart covers 1980 to 1982 model years 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 S1823 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 single-filament design means the 1156 operates at one fixed output level, dedicated solely to the turn signal function.
The International S1823 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/5W output split, fitted with a BAY15d bayonet base.
The dual-filament design of the 1157 allows it to serve two lighting functions from a single housing, with the 21W filament handling the turn signal and the 5W filament typically serving as a running or brake light.
The 1156 and 1157 are not interchangeable. The BA15s base of the 1156 has a single locating pin, while the BAY15d base of the 1157 has two offset pins, making the socket fitments physically distinct.
Both the 1156 and 1157 conform to ANSI standards recognized in the United States and Canada, indicating a shared regional specification framework for these bulb types.