The International 900A front and rear turn signal bulbs both utilize a 198 bulb size. The replacement chart covers 1966 to 1967 vehicle 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 198 bulb is the sole turn signal bulb size listed for the International 900A across both 1966 and 1967, covering front and rear positions under the Light Duty classification.
The 198 is an ANSI-standardized bulb recognized in both the United States and Canada, placing it within a regulated specification framework common to North American automotive lighting.
It follows the T5 miniature wedge form factor, a designation that refers to a tubular bulb approximately 5/8 of an inch wide with a wedge-style base that seats directly into a socket without a separate metal base or pins.
The 198 operates at 12 volts, consistent with the 12-volt electrical systems standard in automotive applications of that era.
At 2 watts, the 198 produces a relatively low power output, which is characteristic of indicator and signal lighting rather than primary illumination functions.
The wedge base design of the T5 form factor means the bulb is held in place by the tension of the socket itself, with no locking mechanism or bayonet pins involved in retention.
Because the same 198 bulb size is specified for both front and rear turn signal positions on the International 900A, the two positions share full bulb interchangeability with one another.