International S1955 Back Up Light Bulb Size

The International S1955 back up light requires a 1156 bulb size for proper installation and function within the lighting assembly. Provided data covers the period from 1981 through 1989 for the specified vehicle and component.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1981-1989	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The International S1955 uses the 1156 bulb for its back up light across the 1981-1989 model years.
The 1156 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard applicable in both the United States and Canada.
The 1156 operates on a 12-volt electrical system and draws 21 watts, which is consistent with standard automotive incandescent back up light applications.
The 1156 is a single-filament bulb, distinguishing it from dual-filament variants such as the 1157, which serves combined stop and tail light functions.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a bayonet mount with a 15mm base width and a single contact pin, making it incompatible with BA15d sockets, which require two offset pins.