The designation F-4L was given to a number of advanced versions of the Phantom that were proposed to the Navy in 1963-64. However, none were ordered into production.
The best-known of these configurations was known as Model 98FOA by the company, and called for the aircraft to be powered by Rolls Royce RB.168-25R Spey turbofans and to be armed with either six Sparrow III missiles or two Phoenix long-range missiles. The increased power made available by the Spey would make the Phantom capable of being operated from smaller aircraft carriers which had previously used the Vought F-8 Crusader for defense. However, any advantages offered by the more powerful engine of the F-4L were deemed to be outweighed by the additional cost and by considerations of commonality. The F-4L project was abandoned before anything could be built.