GMC F350 front and rear side marker bulbs utilize a 63 bulb size across both positions. The replacement chart covers 1953 to 1955 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 GMC F350 (1953-1955) uses the 63 bulb for both front and rear side marker positions.
The 63 bulb follows ANSI standards recognized in the United States and Canada.
It is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as running and braking.
The 63 bulb operates at 12 volts, consistent with standard automotive electrical systems of that era.
At 0.63 watts, the 63 bulb draws very low power, reflecting its role as a marker light rather than a primary illumination source.
The BA9s base is a miniature bayonet fitting, characterized by a 9mm cap width with no locating pins, which distinguishes it from indexed bayonet types.
The front and rear side marker positions on the GMC F350 share an identical bulb specification across all three model years covered, indicating full interchangeability between those positions.