The F4H-1 (F for Fighter, H for McDonnell Aircraft, 4 for the fourth fighter that the Navy was serious about having McDonnell develop) first flew in 1958. It was powered by two J79-GE-2 engines.
Early in the F4H production program, the Navy decided to change to the more powerful J79-GE-8 engine. As a result, the designation of the first 47 F4H-1s that had the early production inlet was changed to F4H-1F in May 1961 when the last one was accepted. (A retroactive redesignation without a configuration change was unusual but not unknown; at least if you give me time, I might think of another one.) The F suffix denoted an engine change. Subsequent production with the -8 engine were still F4H-1s for a short while.
In November 1962 the airplane designations of the Army, Navy, and Air Force were changed to be common and consistent. As a result, the F4H-1F became the F-4A and the F4H-1 became the F-4B, which I have to admit is a more straightforward way of identifying the production configuration change.
The main external difference between the standard production F-4A and F-4B was the engine inlet.*
In addition to the changes shown in the illustration above, the inlet boundary layer discharge system was modified as well: the major difference was in the shape and size of the exhaust vents on the upper side of the nacelle aft of the inlet. The original outlets on the inboard side of the variable ramp were probably deleted.
Most of the F-4As were assigned to training squadrons VF-101 (Oceana, Virginia) and VF-121 (Miramar, California).
Five were used in project LANA to compete for the Bendix Trophy in May 1961, celebrating the 50th anniversary of U.S. Naval aviation (L for 50 + ANA for Anniversary of Naval Aviation). It was a cross-country time-trial race from Ontario International Airport, California to NAS New York. The fastest Phantom averaged 870 mph for two hours and 47 minutes. Three subsonic in-flight refuelings were required.
The last F-4A built, BuNo 148275, was retired in April 1968. It has been on display at the U.S. Naval Academy at Annapolis, Maryland since 1969. It is periodically repainted by the midshipmen in a different squadron's markings.
Robert F. Dorr Collection
*The flush canopy and small radome, which is what most people associate with the early F4H, was only on the first 18 of a total of 47 F4H-1Fs. The remaining 29 had the raised canopy and at least two of the first 18 had the bigger radome. For more on the configurations of the early F4Hs, see http://tailspintopics.blogspot.com/2009/11/early-phantom-iis.html