Ok, so I did not notice there was a separate forum for the diesel Rams, I posted in the 3rd gen. section, as thats the type I'm looking at, most likely a 2002-2007, and here's my post:

I currently have a Durango that is in need of a lot of work, and I'm very seriously considering upgrading to a 3rd generation Ram, either a 2500 or 3500 with the Cummins. My budget is about $15,000, hoping to keep the payment a bit under $300/month, ideally around $250-270 at the most. My main concern is knowing what should I be looking for on one of these trucks thats nearing the 200k mile point, are there any common issues I should know about, I'd imagine that as long as its been well cared for and maintained, 200k miles on such a truck shouldn't be too worn out? I honestly don't have much if any experience with Rams that are this new, and this would be my first diesel truck as well. I've got quite a bit of help in the Durango section over the years, so I guess I'm mostly looking for any advice based on experience that might help me avoid buying a truck that I'd end up regretting deeply once I discover its got far more problems than I expected.

 

The 5.9 Cummins in those year models are still highly sought after. As far as engine goes, many would say that 200k on a 5.9 means its not quite to the halfway point of it's lifespan. As long as you find a truck that has been properly cared for and no signs of obvious abuse, you should be good to go. I, personally am leery of buying a vehicle with a lot of custom mods, but that is just a personal preference.

 

You're right about the mods, honestly I'm looking for something that has been flat stock its entire life, and I'll leave it as such. Since this not only will be towing, it will also be my daily driver, I'm not willing not sacrifice reliability with those things.