Originally Posted by Pedro Dog
I would ask the mechanic why the failure occurred. Did you overheat the truck? In all of my years, the few times I had blown head gaskets, it was usually overheating. When I put my engines back together, I would take the heads and have them magnafluxed for cracks and checked for surface flatness. I would ask the service department if they did that. If they just changed the gasket, I would be unhappy.
If they can't tell you why it failed, and you did not overheat the truck, then I would be worried it would happen again.
Rule #1: Head gaskets do not blow for no reason
Like Pedro Dog, the only time I have ever blown a head gasket on any of my vehicles was due to overheating, i.e., broken belt, damaged radiator/coolant loss, busted hose, busted freeze plug, etc.
Aside from the others' recommendations, once you get the truck back I would want to take it to an independent speed shop & pull all the plugs (all 8) and run a compression test on every cylinder, with special attention being paid to #7. Worth the hour or so's labor it'd take.
An OBDII code of P0307 (#7 misfire) can very easily be caused by a dozen different things, one of them being a hairline crack in the cylinder head, i.e., one that you cannot see without the aid of a black light & inspection fluid. You would want to do this with the head laying on the bench, fully disassembled (valves removed). - tip, number the valves/locations before pulling them out.
See Rule #1, above
Also, any of their shop monkeys can pull it down. Putting it back together takes a well-qualified & well-experienced tech.