GMC PM150 front and rear side marker bulbs utilize a 63 size across both locations. The replacement chart covers 1953 to 1955 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 bulb type 63 is an ANSI-standardized single-filament bulb rated at 12 volts and 0.63 watts, fitted with a BA9s base. Its standardization under ANSI covers both the United States and Canada.
The BA9s base is a miniature bayonet cap with a 9mm body, commonly associated with low-wattage indicator and marker applications in automotive lighting.
At 0.63 watts, the type 63 bulb draws minimal current, which is consistent with its role as a side marker rather than a primary illumination source.
The GMC PM150 uses the type 63 bulb for both the front and rear side marker positions across the 1953 and 1955 model years, meaning the same bulb type serves all four marker locations on the vehicle.
The shared bulb specification across front and rear positions indicates interchangeability between those positions, as both draw from the same ANSI type 63 designation.