Ok got it; a V6 has a different
firing order (1 4 2 5 3 6) to an inline 6 as in the AU Falcon (1,5,3,6,2,4) and different banked paired
firing order; their is actually only 3 coils in the coil pack with each coils serving two cylinders and firing together. So you need one designed for your car presumably the AU Falcon. A V6 one won't work on the inline 6 as the
firing order and pairing of coils is different; the V6 coil pack has the 3 and the 6 paired rather than required 6 and 1 paired. Similarly. you won't be able to use an inline 6 coil pack on a V6.
I have an inline 6 mentality but I guess with the demise of Ford Australia's manufacturing and the death of the Oz inline 6 I will have to (reluctantly) open my mind to V6 thinking.