The International R100 front and rear turn signal bulbs both utilize a 198 size bulb specification. The replacement chart covers vehicle production spanning 1953 to 1955.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The International R100 uses the 198 bulb for both front and rear turn signals across the 1953-1955 model years.
The 198 is an ANSI-standardized bulb type, meaning it conforms to a defined specification recognized across the United States and Canada.
The 198 bulb follows the T5 form factor, which refers to a miniature wedge-base construction with a tubular envelope roughly 5/8 of an inch wide.
At 12 volts and 2 watts, the 198 operates on a standard automotive electrical system and draws a very low current, consistent with small indicator lighting applications.
The wedge base of the 198 bulb is held in place by tension from the socket itself rather than by a bayonet or screw mechanism, which is a defining characteristic of the miniature wedge type.
The International R100 (Light Duty) designation applies uniformly to all listed model years and both turn signal positions, indicating no variation in bulb specification between front and rear fitment for this trim classification.
Because the same bulb number is shared across both the front and rear turn signal positions, the 198 is interchangeable between those two locations on this vehicle.