McDonnell Douglas F-4J Phantom II. Part one.

The McDonnell Douglas F-4J was an improved version of the F-4B that featured improved air-to-air and ground-attack capabilities. Five-hundred and twenty-two aircrafts were manufactured and they were delivered from 1966 to 1972. It was upgraded with the General Electric J79-GE that could deliver 17844lbf (79374Kn) of thrust and the Westinghouse AN/AWG-10 fire control radar which made the F-4J the first fighter in the world with real look-down/shot-down capability, a new integrated missile system and the AN/AJB-7 bombing system in order to improve the ground-attack capabilities.
The squadrons covered in this post are:

• VX-4: The United States Navy's evaluation squadron tested the F-4J together with the F-8 Crusader in 1966. 
• VF-191: After returning from Vietnam, they replaced their F-8 Crusader with the F-4J which they retained until 1978 when they were deactivated.
• VF-74: In early 1972 they started to replace their F-4B by the F-4J, when they returned from Vietnam, where they didn't loose a single aircraft, on board USS America (CV-66). In 1975 they were assigned to the USS Nimitz (CVN-68) where they remained until being replaced in 1982 by the F-4S.
• VF-121: This fleet replacement group was equipped with F-4B and F-4J until it was disbanded in 1980.

Sources:
1. https://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II
2. https://en.wikipedia.org/wiki/List_of_McDonnell_Douglas_F-4_Phantom_II_U.S._operators
3. Salamander Books - The Complete Book of Fighters