American Motors Marlin Back Up Light Bulb Size

The American Motors Marlin back up light requires bulb size 1156 or P21W depending on the specific application. Data for the bulb size chart covers the range from 1965 to 1967.

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
1965-1967	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 1156 is the sole bulb type listed for the American Motors Marlin backup light across the 1965-1967 model years.
The 1156 is an ANSI-standardized bulb, meaning its physical and electrical specifications are governed by a recognized North American standard shared across the United States and Canada.
The 1156 uses a BA15s bayonet base, which is a single-contact bayonet mount with a 15mm base width. The "s" designation indicates a single contact point at the base, distinguishing it from double-contact variants that are not interchangeable with this fitment.
As a single-filament bulb, the 1156 serves one dedicated function per socket. This contrasts with dual-filament bulbs, which serve two functions from a single housing.
The 1156 operates at 12 volts and draws 21 watts, placing it in a moderate output range typical of incandescent backup lighting from this era.
The BA15s base type is a critical fitment detail. A visually similar bulb with a BA15d base (dual-contact) would not seat or function correctly in a socket designed for the single-contact BA15s.