05-07 Pathfinders/Xterras/Frontiers, which all had the VQ40DE, came with NGK #PLFR5A-11 (stock #6240) Laser Platinum spark plugs.
08-12 Pathfinders/Xterras/Frontiers with the VQ40DE came with NGK #DILFR5A11 (Stock #93759) OE Laser Iridium spark plugs.
*NOTE: They never came with #LFR5AIX-11's, which are NGK Iridium IX plugs. These will work, but they are an economy Iridium plug and are only recommended for 60,000 mile intervals. The #PLFR5A-11 Laser Platinums, which like the OE Iridiums are rated at 105,000 mile intervals, will work just fine in place of the OE Iridiums and are much less expensive. Iridium is a denser material than Platinum and is a better material for spark plugs, but the amount of performance difference between the two you will notice is negligible if not non-existent.
08-12 Pathfinders with the VK56DE V8, from what I've been told, also come with the NGK #DILFR5A11 (Stock #93759) OE Laser Iridium spark plugs. What I find interesting is the NGK's site calls for #DILFR5C11 (Stock #5443) OE Laser Iridiums (Rockauto.com lists the #DILFR5A11). I think either would work fine; the difference is in the firing end construction. According to the Nissan catalog, the DILFR5A11 has a "special design" firing end, whatever that means, and the DILFR5C11 has a "low angle ground electrode."
Rockauto.com is a good place for spark plugs. I usually get the Laser Platinums at AdvanceAutoParts.com. I order them online for store pick-up using discount code "TRT30," which gives you 30% off, and they end up costing $9.99/plug + tax. It usually works out a little cheaper than Rockauto because of the shipping cost. As far as the OE Iridiums, I have a hard time finding them in stock at the local Advance Auto Parts stores.
www.ngksparkplugs.com
http://www.ngksparkplugs.com/docs/tech/ ... _plugs.pdf