Mercury Monarch high and low beam headlight bulbs utilize H6054 and H6024 bulb sizes across the vehicle's production specifications. The replacement chart covers 1975 through 1980 model years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercury Monarch uses two distinct sealed beam headlight types across its production run: the H6024 for 1975-1977 models and the H6054 for 1978-1980 models.
The H6054 is a 5x7-inch rectangular sealed beam unit operating at 12V. It conforms to ANSI standards recognized in both the United States and Canada.
The H6024 is a 7-inch round sealed beam unit, also rated at 12V and built to the same ANSI standard applicable in the United States and Canada.
Both the H6054 and H6024 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When the filament fails, the entire unit requires replacement rather than an individual bulb.
On the Mercury Monarch, the high beam and low beam positions use the same bulb size for each model year. The H6054 serves both functions on 1978-1980 models, and the H6024 serves both functions on 1975-1977 models.
The H6054 and H6024 are not interchangeable with each other. The rectangular form factor of the H6054 and the round form factor of the H6024 require different headlight housings, making cross-substitution between the two type groups physically incompatible.