Lincoln Mark II Dome Light Bulb Size

The Lincoln Mark II dome light requires a 1003 bulb size for proper illumination within the interior cabin area. Data for 1003 bulb requirements covers the 1956 to 1957 span.

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
1956-1957	1003

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1003

Other Locations

Additional Notes

The 1003 is an ANSI-standardized bulb used in the United States and Canada, operating at 12 volts with a 21-watt output through a single filament.
The 1003 bulb uses a BA15s bayonet base, which is a single-contact bayonet mount with a 15mm base width.
The Lincoln Mark II uses the 1003 bulb for the dome light across both the 1956-1957 model years.
The single-filament design of the 1003 means it serves one lighting function only, as opposed to dual-filament bulbs that can serve two functions such as running and brake light from a single unit.
The BA15s designation indicates a single-contact base, and substituting a dual-contact BA15d bulb in the same socket would result in an incompatible fitment.