If I might correct Ghost Dancer on a couple of factual matters relating to the E-3D (don't know anything much about C130J). The E-3D carries a Flt Eng as well as 3 Airborne Technicians (ATs). The ATs are full crew members and are paid Flying Pay (but only for the durations of their flying tours). The ATs look after mission equipment (comms, displays and radar respectively) while the Flt Eng is responsible for all the flight systems in the traditional way. Also, none of these people carry out 'servicing' in the air - that is the job of the ground crew. The ATs' primary job consists of operating the equipment, fault diagnosis and only a very limited amount of work to keep it going if necessary. (Apologies to any ATs if I have got the job definitions slightly wrong). There are no plans to remove the Flt Eng from the E-3D (I'm pleased to say).
Finally, I must add what a thoroughly top bunch of chaps the ATs and Flt Engs are - the E-3D world would be a poorer place without them (and grounded).