I bought a 38N Expedition in 2005, still have it. It’s been a good coach. The usual problems; ride ht valves, couple bad slide motors.
I’ll bet a steak dinner it’s a 300 CAT C7. If they tuned it to 350 after factory; beware. The cooling system wasn’t designed to handle it and it didn’t give you any more torque. No complaints with my drive train or chassis, 60K miles.
It’s a Allison 3000, which is fine.
It’s a TPO, not rubber, roof. If I have any words of wisdom, it’s look for leaks. Look around the shower, end caps, etc.
The hitch is rated for 10,000 # BUT a year after I bought it, I got a letter and a new rating label stating it was only good for 5000# unless you added WDHitch, 500# max tongue weight. I remember that making a few buyers angry, didn’t affect me. I towed a 5000# cargo trailer occasionally. BTW, the chassis comes pre wired with seven wire plug including brake power which is buried up in the dash behind the instrument cluster.
Other than that, look for tire age $4K, and there is a big maintenance every five years;
All fluids eg coolant, ps fluid, diff, trans, belts, air filter, air compressor desiccant,
(it’s due hoses) plus oil and filters so I would guess another $5k. My guess is it’s never had it, most don’t.
Look at the dash air close too. Any belt whine when you turn it on?
Good luck, let us know how it turned out.