I was at the dealership this morning having my truck aligned and while in there I started chating with the diesel mechanic who had the cab up on a 6.4. I asked him what was wrong with it and he was installing a new motor. Obviously I asked why and he said it slung #8 rod out the side of the block and then of course the rotating mass destroyed every thing inside,as if the hole in the side wasn't enough. I then proceeded to ask if they have had a lot of trouble out of the 6.4's. He said they (in the past 6 or 7 months) have had 4 total trucks that came in with destroyed blocks/motors. Now 1 of them was on a dyno when it blew up and was seriously chipped up (mechanics words not mine) when it came apart. The other 3 were all stock and all of them had the #8 rod come out the side and HE said it is from the EGR/coolant cooler coming apart and dumping coolant right into the piston hole. On a 6.0 he said there is warning (overflowing degas bottle etc...) but on the 6.4 there isn't any warning. Its just fine one minute and then hole in side of block the next.
Now all of this is what HE said. I don't own one or know much about them. I am just passing the word along so maybe you all can do some thing to prevent it, if thats even possible