relays and fuses

2005 Durango SLT, took off the clutch fan and installed a dual fan with shroud, works awesome, but.....at the moment im connected straight to the battery on the positive and switching the ground....issue im having is the relay is currently switched by the 12vdc power plug (only thing i could find easily that is switched) Anyways.....i need to find an appropriate place to tap into so the fans arnt running when the ignition is off, i was thinking fuel pump power but not sure if thats wise....any better places?. Also, im rewriring the fans and want as clean an install as possible....i found that the power distribution box has 2 open slots for a "carriage" that will hold the 2 40amp relays rather nice and not have an aftermarket relay/fuse block.....anyone know where i can find the little yellow carriage that clips into the power distro box and will hold 2 form C relay coils?