The GMC 150 uses a 63 bulb size for both front and rear side marker applications. The replacement chart covers 1951 to 1955 model 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 150 uses the 63 bulb for both front and rear side marker positions across the 1951-1955 model years.
The 63 bulb is an ANSI-standardized type recognized in both 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, into a shared unit.
The 63 bulb operates on a 12-volt electrical system, consistent with the standard automotive voltage architecture of the period.
At 0.63 watts, the 63 bulb draws a very low amount of power relative to most other automotive bulb types.
The BA9s base is a miniature bayonet fitting, characterized by a 9mm collar with no locating pins, which distinguishes it from indexed bayonet types that require rotational alignment during installation.
The shared bulb specification across both the front and rear side marker positions on the GMC 150 indicates that a single bulb type serves all four side marker sockets on the vehicle.