Diesel Subs, while cool, the 6.5TD had it's quirks
No hard to work on, but know what you are getting into.
94 and newer use a totally electronically controled injection pump, and they are problematic, the FSD ( Fuel solinoid driver AKA Pump Mounted driver PMD ) is a $300 part, and is a frequent flyer. there is also a resitor in the plug connection that a lot of folks don't know about, can cause issues as well.
Injection pumps and lift pumps are an issue, ASK if and WHEN they have been replaced, ask for dated reciepts ! these are expensive parts, and can be the reason they are selling. ( injection pump rebuild will run in the $900 range for a good rebuild, test) Injectors are not usually an issue, but can be, GLOW PLUGS can cause you a world of grief, if they have been replaced recently, be very skeptical, ask if they kept the old ones, very common to break them off in the head and they fall ingo the combustion cup, where they will eventually fall into cyl and get eaten by a valve, now you have head problems.
THe basic 6.5 engine itself isn't bad, depending on care early in life, thought there are some with factory defects.
I'm not trying to scare you, just go in informed, and some what knowledgable.
Finding someone who can or is willing to work on them can be tough, and costly.
You have a PM