Every truck I see with a tuner has had a blown head gasket. One had a cracked block from being overheated several times.

That is a very broad statement. I run a Smarty JR ME tuner on mine and have had it on for 50,000 miles. So far so good. Keep it on Towing tune.

I know it sounds that way, but I have yet to have a modified 6.7 with less than 50k miles come in the door of my shop without a blown head gasket. Well except for my personal truck that got head studs a week after the smarty went on. I don't think I have had a smarty jr truck through my door either though. Every single one I can remember had h&s tuning.

I know my truck is not a 4 gen but I have run well over 100,000 miles on SW 3 on my Smarty SR. I do monitor my gauges. I tow with that power as well.

I guess I am lucky by what I am reading. However, I think it might depend on how you are using that power as well.

Mines over 50k, its been tweaked since day one. Its a bone stock engine, and been run on mild/hot most of the time. So much for that rumor of a story.

Most of that mileage, I've been towing trailers and use mine for work daily, so its not a garage queen. I also run 33in tires on 3.73 gears on a RFE68 transmission. The truck driveline hasn't be serviced either.