It vaies between vehicles, i would sugges getting a Chiltons manual for your specific vehicle...i think they are like 5-10 dollars and have a whole wealth of information specific to your vehicle.
Back plug, passenger side.
ngr 8
Number 8 spark plug location on a 4.6 liter ford 2002. Is located on the Driver Side , Last one near the fire wall...
passenger's side of engine, last one in back.
n-8=x Then whatever integers you plug in will change the answer.
On the drivers side front.
A 2004 Mercury Mountaineer does not have the Coil On Plug ( C.O.P. ) ignition system with ( 8 ) individual coils . It has the Electronic Distributorless Ignition System ( EDIS ) with ( 2 coil packs ) and ( 8 ) spark plug wires
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Lincoln Mark VIII
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front
On the v 8 it is the front driver side cylinder.
firewall 4 - 8 3 - 7 2 - 6 1 - 5 front of Ford Expedition