International Scout II Back Up Light Bulb Size

The International Scout II back up light utilizes bulb size P21W or 199 depending on the specific configuration of the lighting assembly. Data for the lighting components covers the range from 1971 to 1980.

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
1979-1980	P21W
1978	199
1977	P21W
1976	199
1971-1975	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	199

Other Locations

Additional Notes

The P21W is an ECE-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base. It is used across the majority of International Scout II model years covered in these specifications.
The 199 is an ANSI-standard single-filament bulb also rated at 12V and 21W, sharing the BA15s bayonet base. It is classified as a variant of the 1156 bulb type.
Despite originating from different standardization bodies, the P21W and 199 share identical voltage, wattage, and base type, which reflects their functional equivalence in backup light applications.
The International Scout II (1971-1975) and 1977, 1979-1980 model years use the P21W bulb for the backup light position.
The 1976 and 1978 International Scout II model years use the 199 bulb rather than the P21W for the backup light position.
The BA15s bayonet base is a single-contact fitting, distinguishing it from the dual-contact BA15d base. Both the P21W and 199 use this single-contact configuration, which is consistent with their single-filament design.
Because the P21W and 199 share the same base type, voltage, and wattage, either bulb is physically and electrically compatible with the Scout II backup light socket across all listed model years.