Seagrave Fire Apparatus H models utilized high beam headlight bulbs sized H4651 and low beam headlight bulbs sized H4656 or H4652. The replacement chart covers vehicle production spanning 1985 to 1990 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 Seagrave Fire Apparatus H uses the H4651 for the high beam headlight position across all listed model years, 1985-1990, making it the most consistently specified bulb in these specifications.
The H4651, H4652, and H4656 are all ANSI-standardized 4x6-inch rectangular sealed beam units operating at 12V. In sealed beam construction, the filament, reflector, and lens are fused into a single glass envelope, so the entire unit is replaced rather than an internal bulb.
The H4652 is a variant of the H4651. Both share the same 4x6-inch rectangular sealed beam form factor, though they are distinct part numbers and are not confirmed as interchangeable by these specifications.
The low beam position on the Seagrave Fire Apparatus H shows a split between two bulb types. The H4652 is specified for 1986-1989, while the H4656 is specified for 1985 and 1990.
The H4656 and H4651 share the same ANSI form factor and voltage rating but occupy different headlight positions. The H4651 is designated for high beam use, and the H4656 for low beam use, and these roles are not interchangeable within the fitment data provided.
All three bulb types in these specifications conform to ANSI standards recognized in both the United States and Canada, indicating regulatory compliance for North American vehicle lighting requirements.