anything to look for with an engine with this mileage

I would do the exact same things you say, then after about 10k miles, have an oil sample pulled (I would say pull 1 before you buy it, but most dealers change the oil before they sell them, so it would just be a sample on clean oil)

Is this a Pre-DPF engine or does it have the DPF/REGEN system??? If it does, then i would have the filter changed out as well, as 500k is a lot of miles if it has not been done yet. It is quite costly to have done, but better now than a $700 tow bill down the road.

 

Cat used catalytic coverters either in the mufflers or under the cab, toss them!

 

Dyno! Do a blow-by test this will tell you how much ring life you have left then check front and rear covers for leaking oil.If you run the overhead check injectors see if they are OEM or OR injectors.Wouldn't hurt to roll rods and mains I would.

 

I would save my money with main and rod bearings. They aren't like they used to be 15-20+ years ago. They are good for the life of the engine, till inframe time. Good advice with the oil sample. If there are excessive bearing materials in the oil, the sample testing will pick it up.

 

Who owned the truck--and can you get service records--500k is an interesting mileage--if taken care of it is barely broken in--if mistreated--it might be ready for out of frame--and everything in between--but typically that mileage would not scare me at all
Just my $.02

 

How much Idle time ,total engine hours?

 

pull an ecm report, and have cat pull a warranty summary on the engine serial number to see what has been done under warranty also.