The Buick GS 350 front side marker uses a 194NA bulb size while the rear side marker requires a 194 bulb size. The replacement chart covers 1968 to 1969 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Buick GS 350 uses two T10 miniature wedge bulbs across its side marker positions: the 194NA for the front and the 194 for the rear, both for the 1968-1969 model years.
Both the 194NA and 194 are ANSI-standardized bulbs recognized in the United States and Canada, operating at 12 volts and 3.78 watts.
The T10 designation refers to a tubular bulb form with a wedge-style base, a common format in low-wattage automotive marker and courtesy lighting applications.
The 194NA and 194 share identical electrical ratings and the same T10 wedge form, making them physically interchangeable in terms of socket fitment.
The functional distinction between the two is the natural amber glass of the 194NA, which filters the light output to produce an amber color without relying on a colored lens or housing.
In the Buick GS 350, the 194NA is specified exclusively for the front side marker positions on both the 1968 and 1969 models, where amber coloring is required by federal side marker regulations that took effect for the 1968 model year.
The rear side marker positions on the 1968-1969 GS 350 use the standard 194, which emits unfiltered light, consistent with rear marker applications that typically rely on a red lens for the required color output.
Substituting a clear 194 in a front socket designed for the 194NA would affect the amber color output if the housing itself does not provide amber filtration.