The International A112 uses a 198 bulb size for both front and rear turn signal applications. The replacement chart covers 1957 to 1958 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 A112 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 roles.
The wedge base of the 198 relies on tension from the socket contacts rather than a bayonet or screw mechanism to maintain its connection, which is a defining characteristic of the miniature wedge family.
All four turn signal positions on the International A112, front left, front right, rear left, and rear right, share the same bulb specification, which means a single bulb type services the entire turn signal system.
The Light Duty classification noted in the specifications refers to the vehicle trim or application category rather than a property of the bulb itself.
Because the 198 is an ANSI-standardized type, it is subject to interchangeability considerations with other T5 wedge bulbs; substitutions with differing wattage ratings may affect turn signal flash rates if the vehicle uses a load-sensitive flasher relay.