New E350 minibus

[bonanno1]

How's it going, me and a few buddies just bought a 7.3 mini bus with 240k on it.
We are going to pretty much drive around the entire country with it.
I was just wondering what I can do to:
1. keep this thing running great.
2. get the best MPG
3. And keep an eye on any parts i would have to change/replace since it does have 240k

the high pressure oil pump was just replaced
new tires all around
new fuel and air filter
started it cold with no black or white smoke
transmission runs fine

any suggestions would be great
straight pipes, chips diesel fuel additives, tune up, whatever you can throw at me
Thanks