Holy confusion, Batman. What is all this? Let see if I have this straight.
F-4A prototype that never went into production
F-4B USNavy, 1st edition
F-110 about a dozen F-4Bs from USN to USAF for testing
F-4C USAF, 1st edition, basically a B with different landing gear & electronics
F-4D USAF, 2nd edition, better air to air and air to ground electronics
F-4E USAF, 3rd edition, added 20mm gatling gun under the nose & new model of J-79 engine
F-4F Luftwaffe version of USAF F-4E
F-4G USAF Wild Weasel converted from E models
F-4J US Navy 2nd edition, better model of J-79
F-4K British version with Rolls Royce Spey engines for RAF
F-4M British version with Rolls Royce Spey engines for RNavy
F-4N updated US Navy B
F-4S updated US Navy J
RF-4B US Navy and US Marine recce, skinny tires, no bulge in wing
RF-4C USAF recce, fat tires and bulge in wing to hold them
RF-4F Luftwaffe version of USAF RF-4C
F-4EJ Japanese built version of F-4E
F-4G, A Navy F-4B modified with ACLS. Was tested and incorperated into the F-4J.
RF-4J, F-4J with QRC recon pallet in place of forward missile launchers. Navy went with TARPS for the F-14.
F-4L, A single seat F-4E. Never went past the design stage.
F-4P, F-4E with the 23 MM gun in place of the 20 MM. Was tested in the E model but never produced.
F-4Q. F-4J with slats. Turned down by the Navy. Later added to F-4S.
F-4R. Light weight, single seat, non slatted, stripped down, day fighter F-4E to be sold to third world countries. Never went past the design stage. They bought the F-5E and F-5F instead.
There was another one. A F-4E was tested with a different engine but I am not sure if it had a changed designation.