Info on Ram diesel

Hi everyone.

Questions about an 07 Ram 1500 diesel that I want to go look at. The guy says he's replaced the battery, water pump, thermostat, radiator and also coolant sensor. But it runs hot. He says it might need a head gasket. It's 2500 bucks which seems cheep to me. Of course, if he thinks it's toast... My first thought is he's throwing parts at it and has no idea what's wrong, and that it could be simply an indication problem.

Are these engines prone to bad head gaskets? He says it has 220K on it. Anything else that might be the culprit? Are these engines unusually hard to work on/rebuild? This is new territory for me.

Thanks everyone.