Th 6.0's really aren't as bad as everyone hears. Ask Ron, and yes, even with the issues his FLA truck had, he still loves it.
Now this ad... he is selling it over just a bad EGR Cooler for a "buck" he is an IDIOT!!!! No, not like you Brian.........
My guess is the EGR Cooler failed, and instead of heeding the warning signs, which yes they will warn you, like disappearing coolant, white smoke in the exhaust..... he just kept driving it, which in turn, put coolant into the intake, into the cylinders, now we have copious amounts of STEAM and "Pop goes a head gasket"......... just a guess..... but have seen it many times before.....
Just like any other engine.... a lot of problems with the engine, are caused by the loose nut behind the wheel.......... watch what it's doing/telling you and fix it before it breaks..... (Like a leaking timing cover.... fixed before it took out bearings.......) If my above scenario is what happened, if he would have troubleshot the issue when coolant began to disappear, it would have been a few hundred dollars for an EGR Cooler..... or if he lived in a REASONABLE state a couple hundred dollar EGR Delete (one of the best things you can do for a 6.0 IMHO, removes most of the heat from the cooling system to begin with) and on his merry way. Now, the heads need to come off, be gone through, head gaskets, studs to be safe, AND still have to buy a replacement EGR Cooler that was the problem in the first place.........
Maintenance is of the utmost importance with anything mechanical............