The International S100 front and rear turn signal bulbs both utilize a 198 size bulb specification. The replacement chart covers 1956 to 1957 vehicle production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 198 bulb is the sole turn signal bulb type listed for the International S100 across both covered model years, appearing in both the front and rear turn signal positions.
The 198 bulb follows the ANSI standard recognized in the United States and Canada, placing it within a regulated specification framework common to North American automotive lighting.
This bulb operates at 12 volts, which aligns with the standard 12-volt electrical systems used in automotive applications of that era.
At 2 watts, the 198 bulb draws a very low amount of power, reflecting its classification as a miniature lamp rather than a primary lighting source.
The 198 bulb uses a T5 miniature wedge base, a termless connector design that seats directly into a matching socket without requiring a separate metal base or locking pins.
The Light Duty designation associated with the 198 bulb in these specifications indicates it is rated for standard, non-heavy-load signaling applications rather than high-cycle or high-vibration environments.
The front and rear turn signal positions on the International S100 share an identical bulb specification for 1956-1957, meaning a single bulb type services all four turn signal positions on the vehicle.