The Mazda RX-4 uses an H5001 bulb size for high beam headlights and an H5006 bulb size for low beam headlights. The replacement chart covers vehicle production years spanning 1974 to 1978 with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mazda RX-4 uses the H5001 bulb type for high beam headlights across all listed model years, spanning 1974-1978.
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. Because it is a sealed beam, the entire unit is replaced rather than an internal filament or capsule.
The H5006 serves as the low beam headlight across the full 1974-1978 model year range of the RX-4.
The H5006 is a 5.75-inch round sealed beam unit, also rated at 12V and built to the same ANSI standard as the H5001. Like the H5001, the H5006 requires full unit replacement when it fails.
The H5001 and H5006 are physically distinct sealed beam formats. The H5001 is square and smaller, while the H5006 is round and larger, making the two units non-interchangeable with each other.
Both sealed beam types share the same 12V operating voltage, which reflects the standard 12-volt electrical system common to passenger vehicles of this era.
The ANSI designation on both units indicates compliance with a standardized specification, meaning equivalent sealed beams from different manufacturers that carry the same ANSI code are generally interchangeable.