The GMC PM150 front turn signal uses 1034 or 1129 bulb sizes, while the rear turn signal requires 1073 or 1129 bulb sizes. The replacement chart covers 1953 through 1957 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 PM150 uses three distinct bulb types across its front and rear turn signal positions for the 1953-1957 model years: the 1034, 1073, and 1129.
The 1034 and 1129 are both dual-filament bulbs operating at 12V with a 21/5W output, and both use a BAY15d bayonet base, classifying them as variants of the 1157 under the ANSI standard applicable in the US and Canada.
Despite sharing identical electrical ratings and base types, the 1034 and 1129 are separate part numbers and are not confirmed as interchangeable within these specifications.
The 1073 is a single-filament bulb rated at 12V and 13W, fitted with a BA15s bayonet base. It is a lower-wattage variant of the 1156 under the same ANSI standard.
The BA15s base of the 1073 differs from the BAY15d base of the 1034 and 1129. The BAY15d base features offset locating pins to prevent incorrect installation of dual-filament bulbs, while the BA15s base uses a single-contact design suited to single-filament applications.
Because the 1073 uses a BA15s base and the 1034 uses a BAY15d base, these two bulb types are physically non-interchangeable despite both being bayonet-style fittings.
The GMC PM150 front turn signal positions for 1956-1957 use the 1034 bulb, while the 1955 and 1953 model years use the 1129 for the same position.
The rear turn signal positions for the 1956-1957 PM150 use the 1073, whereas the 1955 and 1953 model years use the 1129, meaning the 1129 serves both front and rear positions in those earlier years.
The 1129 is the only bulb type in these specifications that appears in both front and rear turn signal positions, covering the 1953 and 1955 model years across both sub-parts.
The shift from the 1129 to separate 1034 and 1073 bulbs between the 1955 and 1956 model years reflects a divergence in front and rear turn signal bulb specifications for the PM150.