I wish I had access to a cylinder layout for this engine. I would expect the rear most cylinder to be either #7 or #8. I replaced one coil in May of 2011 and this is the first time I have had spark problems since then - approx. 30,000 miles. Hopefully, I will continue on this streak!
I had a diagram when I replaced the last coil and unfortunately do not have it now. At that time I remember thinking the cylinder layout was very strange.
Good luck. Rule of thumb if you haven't read or figure it out is to replace them all. If you are replacing spark plugs and you find out that you have oil on them, then you have leaking valve cover gaskets. More than likely more than that one spark plug will need replacing.
They're not coil packs, they're COPs (Coil-On-Plug).
You need to replace the spark plug at the same time as the coil.
You need to replace all eight coils. The cost of eight coils and plugs is nothing compared to the cost of the catalytic converters.