The Mack CF front and rear turn signal bulb size measures 1157 for both locations on this truck model. The replacement chart covers vehicle production spanning 1981 to 1991 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mack CF uses the 1157 bulb for both its front and rear turn signals across the 1981-1991 model years.
The 1157 is an ANSI-standardized bulb type, meaning its physical and electrical specifications are governed by a recognized North American standard applicable in both the United States and Canada.
The 1157 is a dual-filament bulb, which allows a single unit to serve two distinct lighting functions, typically a lower-intensity running or parking function alongside a higher-intensity signaling function.
The bulb operates on a 12-volt electrical system and carries wattage ratings of 21W and 5W, corresponding to its high- and low-intensity filaments respectively.
The 1157 uses a BAY15d bayonet base, a two-pin offset base type that physically prevents incorrect installation by ensuring the two pins are not symmetrically positioned.
Because the front and rear turn signal positions on the Mack CF share the same 1157 specification, a single bulb type serves both locations without substitution or modification.