The 2004 Ford F-150 5.4L Triton engine's coil packs aren't labeled with letters like "G". They're arranged in two banks of three, on either side of the engine's V configuration. To find the specific coil pack you need to replace (or identify), you'll need to consult a repair manual or a wiring diagram for your specific engine. These diagrams will show the firing order and the corresponding coil pack location for each cylinder.
Without a diagram or knowing which cylinder is malfunctioning, it's impossible to definitively say where "coil pack G" would be. The best approach is to find a diagram online (search "2004 Ford F150 5.4L Triton engine diagram" ) or in a repair manual. That diagram will show you the location of each coil pack relative to the cylinders and will help you troubleshoot.
