[nobb4u]

Just my opinion but you are looking at a truck with a lot of miles, depending on the type of engine you might be looking at a major overhaul in the not too distant future. You did not say what kind of engine but if it is one of the class 7 engines you could be looking at an overhaul in as little as 500,000 miles.
And as I said before this is just my opinion. You might get lucky and get 1,000,000 miles with no problems but I always feel better if I have considered the worse case scenario.