Mercury Monterey Dome Light Bulb Size

The Mercury Monterey dome light utilizes bulb sizes 6411, 211-2, 561, 105, 1003, 1816, and 63 depending on the specific vehicle configuration. Provided data covers a range from 1950 through 2007.

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
2004-2007	6411
1971-1974	561
1956-1970	1003
1950-1955	63

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 36mm length, SV8.5 base. 12V, 5W.	6411
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
ANSI standard (US & Canada). Single-filament bulb with BA9s base. 12V, 0.63W.	63

Other Locations

Additional Notes

The Mercury Monterey dome light specifications span model years 1950 through 2007, with four distinct bulb types used across that period: the 6411, 561, 1003, and 63.
The 1003 is the most frequently specified bulb in these records, covering the Mercury Monterey from 1956 through 1970. It is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The BA15s bayonet base on the 1003 bulb is a single-contact bayonet mount, meaning it is not interchangeable with dual-contact BA15d variants despite sharing a similar physical form.
The 63 bulb was specified for the Mercury Monterey across model years 1950-1955. At only 0.63W, it operates at a significantly lower wattage than any other bulb type in these specifications, and uses a BA9s miniature bayonet base.
The BA9s base on the 63 bulb is physically smaller than the BA15s base used by the 1003, making the two bulbs mutually incompatible despite both being single-filament bayonet types.
The 561 festoon bulb was specified for model years 1971-1974. At 44mm in length and rated at 12W, it is physically longer and draws more than twice the wattage of the 6411 festoon bulb used in later years.
The 6411 festoon bulb was specified for the Mercury Monterey across model years 2004-2007. It measures 36mm in length with an SV8.5 base and is rated at 12V and 5W.
Both the 561 and 6411 are festoon-style bulbs, but their differing lengths (44mm versus 36mm) and contact types mean they are not interchangeable. Installing the wrong festoon length in a fixed-length socket will result in a poor or failed connection.
All four bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada, indicating consistent regulatory classification across the full range of model years listed.
The wattage progression across the four bulb types reflects broader shifts in automotive lighting over the decades, ranging from the 0.63W of the 63 bulb in early 1950s models to the 21W of the 1003 in mid-century models, before returning to lower wattage with the 5W 6411 in 2004-2007 models.