Hello all, I'm a newby too this and have never posted anything. The highest mileage gas engine I've seen has been around 334000. My 2008, 5.7 Hemi quad cab has well passed that by more than 100000. If anyone is still following this and replies I'll fill in more details. If 450,000 + miles is nothing special please let me know. I really want to know what to expect in the next 100,000. Oh it's the original engine and transmission, but the trany just got a new valve body. That is the only major power train repair.