what to look for when buying a newer truck w/ ISX?

[Waterloo]

I would go with the 2350 over the 2250, they are both essentially the same motor. The 2250 was the test bed, the 2350 is a tad more refined... And I'm blowing smoke out my ass, I would prefer the CM-871, but then you are looking at an older truck.

Yes on the Nexiq, but only if it is the real unit, not some Chinese knock off, plenty written on that subject here on the site.

Personally, I would prefer a 13 or 18 over a 10, but that is just me. It is rare to find any 13 or 18 speeds out here anymore, as these new automatics and 2:01 gear ratios are all the rage. The issues are not necessarily the transmissions, but the drivers. These manufacturers, dealers and companies routinely instruct the drivers to lug the motors. When they lug the motors, the forces being applied in the motor internally create havoc and shorten the life of the motor rather quickly. The liners bust loose and take out the heads. The reason you so many of these newer trucks with few miles having already been in framed.

As far as an Owner Operator truck, most of them drive the same way the company drivers do, I have yet to meet anyone out here, owner operator, that knows spit about their Cummins motor. Well, I did meet one guy up in ND, he was more than likely a member of this here site, very up to speed, but that is very rare out here.

And then we have the fuel pumps... That will need to be addressed too. So, plan on spending some money on parts, and tools. Do not depend on these dealers to keep your truck in operational condition, the same goes for warranties, they ain't worth spit.