What's the price of the truck? I have a 14' also. I'd try to figure out what maintenance has been completed on it so far.
Search through the forum and you'll find all the info you'll need. The items you'll want to look up/look at. You'll be getting to a lot of the 100kmiles/6yr service (past the 6 years)
Get under the truck and look it over, look for rust, you'll find posts about the cab corners rusting, look for other signs of rust
Regular engine oil changes
What condition are the tires
Original battery?
Inspect air filter
All the fluids: front & rear diff, transfer case, power steering (try to inspect power steering rack for leaks, weak point on these trucks, and see if any moaning noise or other feedback when turning)
Look at CV boots for tears/leaks
Brakes
Engine coolant
Spark plugs
Belts
Fuse 27 relocation (if not done)
Shocks (vs rebuilding shocks I'd put funds aside to upgrade to 3.0's if planning on any off-roading, in my opinion)
Manual states changing transmission fluid and filter @150k and you'll find many members and posts doing that much, much earlier
I'm sure there's more items someone else can add.
I've done my rear diff fluid and added a dana spicer rear diff cover
Transfer case fluid change
Power steering fluid
A few spark plugs and new wires because of noise heard from the wires arching
I picked my truck up with no off-roading done as well by first owner
Things I'll be doing soon are my front diff fluid, brakes, all new spark plugs wire and ignition coils, belts, coolant + upgrading coolant systems, rebuilding 3.0 shocks
Will eventually address transmission fluid and filter but haven't yet because truck shifts damn smooth