Mercury Commuter front and rear turn signal bulbs utilized sizes 1157NA, 1034NA, 1157, and 1034 depending on production specifications. The replacement chart covers 1957 through 1968 model years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercury Commuter turn signal specifications cover model years 1957-1968, spanning both front and rear positions across twelve years of production.
All four bulb types listed across these specifications, the 1157, 1157NA, 1034, and 1034NA, share the same BAY15d bayonet base and operate at 12V with a dual-filament configuration rated at 21W and 5W. The BAY15d base features two offset pins that lock the bulb into position and allow the socket to distinguish between the two filaments.
The 1034 and 1034NA are each described as variants of the 1157 and 1157NA respectively, meaning they share the same base type and voltage rating but differ in filament output characteristics.
The "NA" suffix on the 1157NA and 1034NA designates natural amber glass, meaning the color is built into the bulb itself rather than produced by a colored lens or housing.
For the Mercury Commuter front turn signal, the 1034 and 1034NA types were used across the majority of listed years, appearing in 1957-1962 and 1965-1966 respectively, while the 1157 and 1157NA types covered 1963-1964 and 1967-1968.
The rear turn signal position on the Mercury Commuter used the 1034 bulb for 1957-1962 and transitioned to the 1157 for 1963-1968, with no amber variants specified for the rear in any year.
Because the 1034 and 1157 share the same BAY15d base, physical installation into the socket is possible regardless of year, but substituting one for the other without confirming the correct variant for a given year may not satisfy original equipment specifications.
The front and rear turn signal positions do not always share the same bulb type within a given model year. In 1963, for example, the front position calls for the 1157 while the rear also calls for the 1157, but in 1965-1966 the front uses the 1034NA while the rear uses the standard 1157, making position-specific fitment relevant.