The International A120 uses a 198 bulb size for both front and rear turn signal applications. This replacement chart covers 1957 to 1958 vehicle production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The International A120 uses the 198 bulb for both front and rear turn signals across the 1957-1958 model years.
The 198 is an ANSI-standardized bulb, meaning it conforms to a defined set of electrical and physical specifications recognized across the United States and Canada.
The 198 bulb follows the T5 miniature wedge form factor, a designation that refers to a tubular glass envelope approximately 5/8 of an inch wide with a wedge-style base that seats directly into a socket without a separate metal cap.
The 198 operates at 12 volts and draws 2 watts, placing it among the lower-output bulbs in automotive applications, consistent with its use in signaling rather than illumination functions.
The wedge base design of the 198 means the bulb is retained by the tension of the socket itself rather than by a bayonet or screw mechanism, which affects how the bulb is seated and removed.
The specifications designate the A120 fitment under a Light Duty classification, which indicates the vehicle falls within a lighter weight or load rating category within the International truck lineup.
The identical bulb size across all four positions, both front and rear turn signals for 1957-1958, reflects a uniform electrical specification throughout the turn signal circuit on the A120.