GMC PM253 front and rear turn signal bulbs both utilize a 1129 size bulb for proper operation. The replacement chart covers 1952 through 1955 model 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 PM253 uses the 1129 bulb across both its front and rear turn signal positions for the 1952-1955 model years.
The 1129 is an ANSI-standardized bulb type, meaning its physical and electrical specifications conform to a defined industry standard recognized in both the United States and Canada.
The 1129 is a dual-filament bulb, which means it contains two separate filaments within a single envelope, allowing it to serve more than one lighting function.
The 1129 uses a BAY15d bayonet base, a two-pin offset bayonet mount where the two pins are positioned at different heights to ensure the bulb can only be inserted in one orientation, preventing incorrect filament alignment.
The 1129 operates at 12 volts with a wattage rating of 21/5W, where the higher wattage corresponds to the brighter filament and the lower wattage to the dimmer filament.
The 1129 is described as a variant of the 1157 bulb type. While both share the BAY15d base and dual-filament design, they are not identical and are not confirmed as interchangeable in this application.