International S1624 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 S1624 uses two distinct bulb types across its turn signal positions for the 1980-1982 model years: the 1156 at the front and the 1157 at the rear.
The 1156 is a single-filament bulb operating at 12V and 21W, fitted with a BA15s bayonet base. The single filament means it serves one lighting function only, which aligns with its use in a dedicated front turn signal position.
The 1157 is a dual-filament bulb rated at 12V with two wattage outputs, 21W and 5W, and uses a BAY15d bayonet base. The dual-filament design allows it to serve two separate lighting functions from a single housing, such as turn signaling and running light operation simultaneously.
The BA15s base of the 1156 and the BAY15d base of the 1157 are not interchangeable. Although both use a 15mm bayonet-style base, the BA15s has a single contact pin while the BAY15d has two offset contact pins, making physical substitution between the two impossible without modification.
Both the 1156 and 1157 conform to ANSI standards recognized in the United States and Canada, indicating standardized electrical and physical tolerances across manufacturers producing these bulb types.
The International S1624 (1980-1982) maintains consistent bulb specifications across all three model years, with no variation in bulb type for either the front or rear turn signal positions during that period.