I currently have almost 125,000 miles on mine. I got it with 30,000. I changed the plugs at 105,000. Truck was still running good, but just felt the need to change 'em. Ran better, picked up about 1.5mpg afterwards. No broken plugs, no blowouts, no problems. I used the same Motorcraft plugs that came out and have not had any problems. I torqued 'em down 14ftlbs as recommended. If you can find my thread where I changed them, you'll see a little more.

Oh, I also tow a 26' travel trailer, and have a 4100 pound boat I pull. So, there's my story. Real world stuff.