GMC FC150 front and rear side marker bulbs utilize a 63 size across both positions. The replacement chart covers 1950 to 1952 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC FC150 uses the 63 bulb for both front and rear side marker positions across the 1950-1952 model years.
The 63 is an ANSI-standardized bulb type recognized across the United States and Canada, indicating a standardized form factor and electrical specification.
The 63 bulb operates on a 12-volt system, consistent with the 12V electrical architecture standard in automotive applications of that era.
At 0.63 watts, the 63 bulb draws very low current, reflecting its role as a marker light rather than a primary illumination source.
The 63 bulb uses a BA9s base, a miniature bayonet-style single-contact base with a 9mm collar width, commonly found in low-wattage indicator and marker applications.
The single-filament construction of the 63 bulb means it serves one lighting function only, with no dual-mode capability such as combined running and brake signaling.
The front and rear side marker positions on the GMC FC150 share the same bulb specification, meaning a single bulb type services all four side marker sockets on the vehicle.