Mercury Cyclone front and rear turn signal bulbs utilize 1157, 1157NA, and 1034NA sizes, with front positions accommodating multiple bulb options and rear positions requiring 1157 size. The replacement chart covers 1964 through 1971 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 1157 and 1157NA bulbs are the most frequently specified types across the Mercury Cyclone's turn signal positions, appearing in both front and rear applications across the 1964-1971 model range.
All three bulb types listed in these specifications, the 1157, 1157NA, and 1034NA, share the BAY15d bayonet base and operate at 12V with a dual-filament output of 21W and 5W, where the higher wattage filament serves the turn signal function and the lower wattage filament serves a secondary running light function.
The 1157NA and 1034NA designations indicate natural amber glass envelopes, which produce an amber signal color directly from the bulb rather than relying on a colored lens.
The 1034NA is noted as a variant of the 1157 and shares the same BAY15d base and 12V/21W/5W electrical ratings, though the two are distinct ANSI part numbers and are not necessarily interchangeable without verification.
The Mercury Cyclone (1967-1969) specifies the 1157NA for the front turn signal, meaning those positions require the natural amber glass version rather than the clear 1157.
The front turn signal positions for the 1965-1966 Mercury Cyclone use the 1034NA, while the rear positions for those same years use the standard 1157, indicating that the front and rear positions do not share the same bulb specification for those model years.
For the 1970-1971 Mercury Cyclone, both the front and rear turn signal positions share the same 1157 specification, making those the only years where a single bulb type covers all four turn signal sockets.
The 1964 Mercury Cyclone specifies the 1157NA for the front turn signal and the 1157 for the rear, following the same front-to-rear distinction seen in later model years that use the NA-suffix bulbs up front.
All three bulb types conform to ANSI standards recognized in both the United States and Canada, placing them within a standardized North American automotive lighting classification system.
Because the 1157NA and 1034NA carry natural amber glass, substituting a clear 1157 in a position originally specified for an NA-suffix bulb may alter the color output of the signal if the corresponding lens is clear or lightly tinted rather than amber.