Mercury Comet Dome Light Bulb Size

The Mercury Comet dome light utilizes bulb sizes 211-2, 561, and 1003 for interior illumination. Available information covers the range of years from 1960 through 1977 for the specified vehicle.

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
1974-1977	211-2
1971-1973	561
1960-1969	1003

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	211-2
ANSI standard (US & Canada). Festoon bulb, 44mm length, end-cap contacts. 12V, 12W.	561
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1003

Other Locations

Additional Notes

The Mercury Comet dome light bulb specifications span the 1960-1977 model years, with three distinct bulb types used across that period: the 1003, the 561, and the 211-2.
The 1003 bulb was fitted to the Mercury Comet from 1960-1969, making it the longest-running dome light specification across the model's history in these records.
The 1003 is a single-filament bulb with a BA15s bayonet base, operating at 12V and drawing 21W, which is notably higher wattage than the two bulb types that followed it.
The BA15s bayonet base on the 1003 is a single-contact fitting, distinguishing it from festoon-style bulbs and requiring a socket designed specifically for that base type.
The 561 bulb was specified for the 1971-1973 model years, representing a transition away from the bayonet-base design to a festoon format.
The 561 is a festoon bulb measuring 44mm in length with end-cap contacts, operating at 12V and 12W, which is a lower wattage than the 1003 it replaced.
The 211-2 bulb was specified for the 1974-1977 model years and is also a festoon type, but it uses an SV8.5 base rather than the end-cap contacts found on the 561.
The 211-2 measures 41mm in length, making it 3mm shorter than the 561, and the differing base styles mean the two festoon bulbs are not interchangeable despite sharing the same 12V, 12W electrical rating.
All three bulb types conform to ANSI standards applicable in both the United States and Canada.
Because the 1003 uses a bayonet base while the 561 and 211-2 are festoon types, none of the three bulbs specified across the Comet's production years are physically interchangeable with one another.