The International R100 uses 194 bulb size for front side marker applications and 97 bulb size for rear side marker applications. The replacement chart covers 1953 to 1955 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 R100 uses two distinct bulb types across its side marker positions for the 1953-1955 model years: the 194 at the front and the 97 at the rear.
Both the 194 and 97 bulbs conform to ANSI standards recognized in the United States and Canada.
The 194 is a miniature wedge bulb in the T10 form factor, rated at 12 volts and 3.78 watts, and is designated for the front side marker position across all listed model years.
The T10 wedge base of the 194 bulb connects by friction fit rather than a bayonet or screw mechanism, which distinguishes it physically from the rear bulb used in the same vehicle.
The 97 bulb is a single-filament type mounted on a BA15s bayonet base, rated at 12 volts and 13 watts, and serves the rear side marker position across all listed model years.
The BA15s designation indicates a single-contact bayonet base with a 15mm collar, which is not interchangeable with dual-contact bayonet bases such as BA15d.
The 97 is noted as a variant of the 1156 bulb family, though the two are not identical and substitution between them warrants verification of wattage and base compatibility before use.
The wattage difference between the front and rear bulbs is substantial, with the rear 97 bulb drawing roughly 3.4 times more power than the front 194 bulb, reflecting the greater illumination demands typically placed on rear marker positions.