Peterbilt 379 front side marker bulbs measure 194 in size, while rear side marker bulbs measure 1816, with each bulb type specified for optimal illumination. The replacement chart covers vehicle production spanning 1986 to 2007, detailing bulb specifications across the entire model generation.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Peterbilt 379 uses the 194 bulb for the front side marker position across all listed model years from 1986-2007, making it the most consistently specified bulb in these fitment records.
The 194 is an ANSI-standard miniature wedge bulb with a T10 envelope, rated at 12 volts and 3.78 watts, and is recognized under both US and Canadian standards.
The rear side marker position on the Peterbilt 379 uses the 1816 bulb for model years 1986-1997.
The 1816 is an ANSI-standard miniature wedge bulb with a T3.25 envelope, rated at 12 volts and 4 watts, also recognized under both US and Canadian standards.
Although both the 194 and 1816 are miniature wedge-base bulbs operating at 12 volts, their T10 and T3.25 envelope sizes are not the same, meaning the two bulbs are not interchangeable between front and rear side marker positions.
The wattage difference between the 194 (3.78W) and the 1816 (4W) reflects a slight variation in light output and current draw, which corresponds to their respective front and rear marker applications.
The T10 designation of the 194 bulb refers to a tube envelope that is 10 eighths of an inch wide, while the T3.25 designation of the 1816 refers to a narrower envelope measuring 3.25 eighths of an inch wide, resulting in a physically smaller bulb body for the rear marker application.