Toyota Repair: Spark Plugs - Iridium, spark plug wires, iridium plugs

Question
I own a 2001 Toyota Seinna.  It has a V-6 3000 series engine with 55,000 miles.  I usually do my own repairs. The manual recommends Iridium plugs every 60,000 miles.  This engine does not have the typical spark plug wires.  I am having a problem locating the six spark plugs. After taking off the plastic engine cover, I noticed three round covers each having electrical wires attached to them. Could these be spark plugs with their own ignition coil.  If so, where could I locate the other three plugs?  Is there anything special about installing Iridium Plugs?

Regards....Joe

Answer
The spark plug coil packs you can see on the front are for cylinders #2,4 and 6, # 1,3and 5 are located on the valve cover under the intake chamber. There are three coil packs, each one fires two cylinders so there are only connectors on the rear bank, these are a little difficult to get to but it can be done with the right tools.
I don't recall this engine using iridium plugs, I thought they were platinum tipped,(but I could be wrong) these need to be replaced at 60,000 miles, the iridium spark plugs last 90,000 miles.