The GMC K3500 side marker utilizes a 194 bulb size for illumination across all listed vehicle applications. Data for the specified component covers the range from 1995 through 2000.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 194 and 168 bulb types are the two sizes specified across all front and rear side marker positions on the GMC K3500, with the 194 being the more widely used of the two across the model's production span.
Both the 194 and 168 are ANSI-standardized miniature wedge bulbs sharing the same T10 form factor and 12-volt operating voltage, meaning the physical connector type is identical between them.
Despite sharing the same T10 form factor, the 194 and 168 are not interchangeable, as they differ in wattage. The 194 draws 3.78W while the 168 draws 4.9W, making the 168 the higher-wattage of the two.
The front side marker on the GMC K3500 used the 168 bulb from 1979-1986, then transitioned to the 194 bulb starting with the 1988 model year.
The 1990-1991 front side marker 194 bulb fitment carries a conditional note specifying applicability to vehicles equipped with Halogen Capsule Headlamps.
The rear side marker position uses the 194 bulb exclusively across all years listed in the specifications, with no equivalent use of the 168 bulb in that position.
The front and rear side marker positions share the same 194 bulb size for all model years from 1993-2000, indicating uniform bulb fitment across both marker locations during that period.