The Isuzu i-370 turn signal utilizes a 3757NA bulb size for the front lighting assembly. Data for the specific component covers the range from 2007 to 2008.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Isuzu i-370 uses two distinct bulb types across its turn signal positions for the 2007-2008 model years: the 3757NA at the front and the 3057 at the rear.
Both the 3757NA and 3057 are ANSI-standardized bulbs recognized in the United States and Canada, and both operate on a 12-volt electrical system.
Each bulb type follows the T25 wedge form factor, which refers to a wedge-base design with a 25mm envelope width, allowing tool-free insertion into compatible sockets.
Both bulbs carry dual-filament construction, meaning each contains a high-intensity filament and a low-intensity filament within a single housing, serving separate functions such as turn signaling and running light operation.
The 3057 rear turn signal bulb is rated at 27W on its high-intensity filament and 7W on its low-intensity filament, reflecting the power draw difference between active signaling and steady illumination states.
The 3757NA front turn signal bulb is distinguished by its natural amber glass envelope, which filters the light output to produce an amber color without relying on an amber-tinted lens or housing.
The "NA" suffix in the 3757NA designation specifically denotes the natural amber glass coating, setting it apart from clear-glass variants in the same bulb family.
Although the 3757NA and 3057 share the same T25 wedge base and 12-volt rating, they are not interchangeable between front and rear positions on the Isuzu i-370, as the front position requires the amber-coated variant.