The Mack Pinnacle front turn signal requires a 3457NA bulb size while the rear turn signal uses a 1157 bulb size. The replacement chart contains specifications covering 2011 through 2017 production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mack Pinnacle uses two distinct bulb types across its front and rear turn signal positions for the 2011-2017 model years: the 3457NA for the front and the 1157 for the rear.
Both the 3457NA and 1157 are ANSI-standardized bulbs recognized in the United States and Canada, meaning they conform to defined performance and dimensional standards shared across manufacturers.
Both bulb types operate on a 12-volt electrical system and feature dual-filament construction, which allows a single bulb to serve two brightness levels within the same housing.
The 3457NA is a T25 wedge-type bulb rated at 27W on its high filament and 7W on its low filament, giving it a notably wide power ratio between the two filaments compared to the 1157.
The 3457NA carries natural amber glass, meaning the color is built into the bulb itself rather than produced by a colored lens, which is a relevant factor when the housing uses a clear or translucent cover.
The 1157 uses a BAY15d bayonet base, a two-pin offset bayonet mount that is physically keyed to prevent incorrect orientation during installation.
The 1157 is rated at 21W and 5W across its two filaments, making it a lower-wattage bulb overall than the 3457NA front unit.
The 3457NA and 1157 are not interchangeable with each other, as they differ in base type, wattage, glass color, and bulb form factor, meaning each position requires its specific bulb.