Dodge D400 Headlight Bulb Size

Additional Notes

• The Dodge D400 headlight specifications cover the 1978-1981 model years, with all listed bulb types being sealed beam units operating at 12V under ANSI standards recognized in both the United States and Canada.
• Sealed beam units are self-contained assemblies in which the filament, reflector, and lens are fused into a single housing. When a sealed beam fails, the entire unit is replaced rather than an internal bulb.
• The H6054 is a 5x7-inch rectangular sealed beam unit used in the 1981 D400 for both high and low beam functions, meaning a single unit type serves both lighting roles in that year.
• The H6024 is a 7-inch round sealed beam unit and appears across 1978-1980 in two-headlamp configurations, serving both high and low beam positions in those applications.
• The Dodge D400 (1979-1980) with a four-headlamp configuration uses 4x6-inch rectangular sealed beam units, a physically smaller format than the 7-inch round H6024 used in the two-headlamp setup of the same years.
• In four-headlamp configurations, the high beam and low beam positions use distinct bulb types despite sharing the same 4x6-inch rectangular format. The H4651 serves the high beam, while the H4652 and H4656 serve the low beam in 1980 and 1979 respectively, and these units are not interchangeable across those positions.
• The H4652 is a variant of the H4651, both being 4x6-inch rectangular sealed beam units. Their designation difference reflects functional specialization rather than a physical housing difference.
• Fitment in the 1979 and 1980 model years is conditional on headlamp count, meaning the correct replacement unit cannot be determined by year alone without confirming whether the vehicle carries a two-headlamp or four-headlamp arrangement.