Jeff, welcome to NICO. Like any car, they are in the cylinder head. I believe the VG30DE is like the VH45DE in being a coil on plug design.
If your car didn't include a FSM, you may get one at
http://www.nissan-infotech.com/infiniti/ in Acrobat format for a one day subscription. Don't forget to get the Technical Service Bulletins also. Owner's manuals for the cars covered are downloadable for free.
have you been to Carlos'
http://www.fuzzycats.com J30 site? Very useful. For parts, the sponsors on the left are the best.