If you ever need to rebuild the engine, buy a 6.5, and do whatever wiring updates, etc, necessary. It should bolt right in. The 6.2 is well known for cracked blocks (yes, I am in the industry), and aren't worth rebuilding. The 6.5 fares better, but still isn't anything to brag about. We just sold another one this week. The guy had to buy a reman, built on a 6.5L block outright. No core- cracked block. Bummer dude! No wonder so many of them ended up a gas repowers. I do have to give them some credit though, they are better than the worlds worst V8 diesel, also a GM product (see a pattern?), the 5.7L. Go buy a Dodge with a Cummins diesel and a manual transmission, throw away everything made by Dodge, and re-use the rest. That will give you at least a good engine, transmission and rear end.