Mercury Commuter high beam headlight bulbs measure H5001 in size, while low beam headlight bulbs measure H5006 in size. The replacement chart covers vehicle production spanning 1957 to 1968.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercury Commuter uses two distinct sealed beam headlight units across its 1957-1968 model years: the H5001 for high beam and the H5006 for low beam.
The H5001 is a 4-inch square sealed beam unit operating at 12V. It conforms to ANSI standards recognized in both the United States and Canada.
The H5006 is a 5.75-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 H5001 and H5006 are sealed beam units, meaning the lens, reflector, and filament are fused into a single assembly. When a filament fails, the entire unit requires replacement rather than an internal bulb swap.
The H5001 and H5006 are not interchangeable with each other. Their differing form factors, one square and one round, along with their separate high beam and low beam functions, make each unit specific to its designated position.
The H5001 high beam fitment remained consistent across all twelve model years covered in the specifications, from 1957 through 1968, with no variation in bulb size recorded for the Mercury Commuter.
The H5006 low beam fitment similarly held constant across the full 1957-1968 span without any recorded change in bulb size.
The square profile of the H5001 and the round profile of the H5006 reflect a headlight system design common to North American vehicles of that era, where sealed beam standardization was mandated to ensure uniform light output and unit interchangeability across manufacturers.