Mack CH Headlight Bulb Size

Additional Notes

• The Mack CH uses sealed beam headlight units across all three headlamp configurations for model years 1989-1997. Sealed beam units integrate the filament, reflector, and lens into a single assembly, meaning the entire unit is replaced rather than an individual bulb.
• All sealed beam types specified for the Mack CH operate at 12V and conform to ANSI standards recognized in both the United States and Canada.
• The two-round-headlamp configuration uses the H6024 for both high and low beam functions across 1989-1997. The H6024 is a 7-inch round sealed beam unit, and its use in both beam positions means a single unit type serves the full headlighting system on that configuration.
• The four-round-headlamp configuration uses the H5001 for high beam and the H5006 for low beam. The H5001 is a 4-inch square sealed beam unit, while the H5006 is a 5.75-inch round unit, making these two physically distinct assemblies despite appearing in the same headlamp count configuration.
• The four-rectangular-headlamp configuration uses 4x6-inch sealed beam units for both beam positions, but the high beam type (H4651) and the low beam types (H4652 or H4656) are distinct variants. The H4652 and H4656 are not interchangeable with the H4651, even though all three share the same 4x6-inch rectangular form factor.
• Within the four-rectangular low beam position, the specification lists H4652 for model years 1995 and 1997, while H4656 is listed for 1989-1994 and 1996. These are separate part numbers and are not specified as interchangeable with one another.
• The H5001 is described as a 4-inch square sealed beam unit. Despite the square housing, it is classified within the round headlamp group in the specifications, as it appears under the four-round-headlamp configuration.
• Because all units across every configuration are sealed beams, fitment is determined by the physical housing type of the vehicle rather than by a bulb socket or base type. Installing a unit from a different configuration would require a physically incompatible housing.