Cadillac Series 75 Fleetwood Turn Signal Bulb Size
The Cadillac Series 75 Fleetwood front and rear turn signal bulb sizes include 1157, 1034, and 1154 configurations. The replacement chart covers 1950 to 1964 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 Cadillac Series 75 Fleetwood uses three bulb types across its front and rear turn signal positions: the 1034, the 1154, and the 1157, all of which are dual-filament bulbs operating under ANSI standards applicable in the United States and Canada.
All three bulb types share the BAY15d bayonet base, a two-pin offset base design that physically locks the bulb into the socket through a twist-and-lock motion.
The 1034 is the most frequently specified bulb across these turn signal positions, covering the Cadillac Series 75 Fleetwood from 1953-1963 for both front and rear locations.
The 1034 is classified as a variant of the 1157 and carries the same 12V, 21W/5W dual-filament rating, with the wattage split indicating a higher-output filament for the turn signal function and a lower-output filament for a secondary function such as parking or running light duty.
The 1157 replaced the 1034 in the 1964 model year for both front and rear turn signal positions, with both bulbs sharing identical voltage and wattage ratings at 12V, 21W/5W.
The 1154 is specified for the 1950-1952 model years across both front and rear positions and is described as an older variant of the 1157, rated for either 6V or 12V operation, reflecting the transitional electrical system standards of that era.
Because the 1034 and 1157 share the same BAY15d base and identical 12V, 21W/5W ratings, the two bulbs are closely related, though they remain distinct ANSI part numbers and are not formally listed as interchangeable within these specifications.
The 1154, while sharing the BAY15d base with the other two types, carries a dual-voltage rating rather than a fixed 12V rating, which distinguishes it electrically from the 1034 and 1157 and reflects its use in an earlier period of automotive electrical standardization.