American Motors American Back Up Light Bulb Size

The American Motors American back up light utilizes bulb sizes 1156, P21W, and 1073 for the rear illumination system. Data for the specific lighting components covers the range from 1958 to 1968.

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
1961-1968	1156
1960	1073
1958-1959	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	1073

Other Locations

Additional Notes

The 1156 bulb is the dominant back up light specification across the American Motors American lineup, appearing in ten of the eleven model years listed, spanning 1958-1959 and 1961-1968.
The 1156 is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, a single-contact base type widely used in North American automotive lighting applications.
The 1073 bulb is specified for the 1960 American Motors American back up light, making it the sole exception within the listed model years.
The 1073 shares the same ANSI-standard single-filament design and BA15s bayonet base as the 1156, and operates at the same 12V supply voltage.
The key electrical difference between the two bulb types is wattage: the 1073 is rated at 13W, while the 1156 is rated at 21W, meaning the 1073 produces a lower light output under the same voltage.
Because both bulbs share the BA15s bayonet base, they are physically interchangeable in terms of socket fitment, though substituting one for the other results in a difference in light output due to the wattage gap.