Re: F4 Phantom - Flying Bus???
Moreover, the FAA never operated any other F-4 model than the F-4K with RR Spey engines as the Phantom FG1. These were based on the F-4J but were substantially modified to operate from the RN's smaller carriers. Later the aircraft were transferred to the RAF. The RAF operated the F-4M version as the Phantom FGR2 which also had Spey engines, although the preference had been for J79s. However, politics dictated that the '50/50' Phantom should have RR Speys.
Later, to meet the NATO commitment, the RAF acquired 15 ex-USN F-4J models from desert storage. These were flown back to the UK in batches from North Island, refuelling from the then new VC10K2s from Miramar on Operation Tiger Trail in 1983-4. In UK service, these were flown by 74 Sqn from RAF Wattisham as the F-4J(UK), not as spotter magazines would have it, as the Phantom F3. They were retired in 1991; 74 then operated the FGR2 until it was disbanded.
The Spey produced more thrust than the J79 at low level, but the F-4M/K were draggier than all other Phantoms due to their bigger intakes. Thus the UK operated the most powerful, most expensive, heaviest and slowest versions of the jet.
Wattisham was a tad short for the J79 engined aircraft with 8 missiles, hence the F-4J(UK)s were usually flown in Bravo fit with a single centreline tank rather than in Charlie fit with wing mounted Sargent Fletcher tanks.