How good (longevity) is a this engine in the trucks? Just wondering how many miles before things start going south. I am experienced with the diesels, but know nothing about the gas engine. Looking at one with 174000 miles but wonder what will go wrong

If they get hot the valve seat drops out and screws everything up. I have seen some where a rod randomly breaks for absolutly no reason, clean break maintnance don't matter they just snap, bearings usually look new still at 200,000 miles, bores are usually still good then also. Just don't let it get hot. The snapping rod seems to be limited to 03-04 in my experience. Those are the only reasons I have seen the 03-08 hemi get replaced and I own a full service repair shop so we do lots of engine swaps in all makes and models.