I put NGK Iridiums in my truck at 100K. Now at 107K and I'm pleased with performance. Great plugs. As much trouble as it is to change them I didn't want to do it again for another 100K.
06 Black LT 2WD (original owner) - Vector tune, CAI & HSRK, Alvin's trans cooler (brake duct mount), braided stainless brake lines