International SA122 front and rear turn signal bulbs both use 198 size bulbs for replacement applications. The replacement chart covers 1956 to 1957 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 type listed for the International SA122, appearing across both front and rear positions for the 1956-1957 model years.
The 198 bulb follows the ANSI standard, meaning it conforms to a recognized North American specification used in both the United States and Canada.
It is classified as a miniature wedge bulb with a T5 envelope, which refers to a tubular glass form roughly 5/8 of an inch wide that connects to its socket via a wedge-shaped base rather than metal pins or a bayonet fitting.
The 198 bulb operates at 12 volts and draws 2 watts, placing it at the low end of the power range for automotive signal lighting.
The Light Duty designation applied to the 198 fitment indicates these specifications correspond to the lighter vehicle configuration of the SA122 rather than a heavier commercial variant.
Because the same bulb number is listed for both the front and rear turn signal positions across both model years, the 198 is fully interchangeable between those four positions on the International SA122.