This and the K model are unique among Phantoms. Powered by a Spey turbofan they had considerably more thrust than the J-79 powered F-4's. They could climb and excellerate faster but their max speed was slower, only about mach 2.1 - 2.2
This was due to the enlarged intakes and exhaust to incorporate the bigger turbofans causing increased drag.
The airframe was basically an F-4J airframe. 10/10/2002 @ 13:19 [ref: 5865]