The Dodge D300 uses H6024 and H4651 bulbs for high beam headlights and H6024 and H4656 bulbs for low beam headlights, with these bulb sizes representing the specific specifications for this model. The replacement chart covers 1975 to 1980, detailing the bulb specifications across the vehicle production years within that range.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The H6024 is a 7-inch round sealed beam unit operating at 12V and conforming to ANSI standards recognized in both the US and Canada. As a sealed beam, the entire unit is replaced rather than an internal filament or capsule.
The H4651 and H4656 are both 4x6-inch rectangular sealed beam units, also rated at 12V and built to the same ANSI standard. Like the H6024, neither accepts a replaceable internal bulb; the whole assembly is the serviceable component.
The Dodge D300 used the H6024 exclusively across the 1975-1978 model years for both high beam and low beam headlight positions, indicating a single-unit sealed beam system during that period.
For 1979-1980, the D300 with a two-headlamp configuration retained the H6024 for both high and low beam positions, maintaining the same fitment as earlier model years.
The four-headlamp configuration available on the 1979-1980 D300 splits the high beam and low beam functions between two distinct bulb sizes: the H4651 handles the high beam position, while the H4656 handles the low beam position. These two rectangular sealed beam types are not interchangeable with each other despite sharing the same physical form factor.
The H4651 and H4656 are dedicated to their respective beam positions by design. Installing one in place of the other would result in incorrect light output for that position, as each sealed beam unit is internally configured for a specific function.
The H6024 round sealed beam and the H4651/H4656 rectangular sealed beams are not interchangeable, as they differ in both shape and mounting configuration. Selecting the correct type depends on whether the vehicle was built with a two-headlamp or four-headlamp system.