I have owned a few of these trucks
1-2004.5 auto 2wd
1-2005 auto 2wd
1-2005 G56 4x4
1-2006 auto 2wd
and I now have a 2014 2wd with the Aisin in it
all have been great trucks if you get a common rail 5.9 I would add a extra 2 micron filter to help with the injectors.

Bosch makes the injectors and they call for the fuel to be filtered down to 2 micron but the factory Dodge filter is only 7 micron and that is where most of the injector failures come from.

The 48re is not as bad as a lot of people make them out to be, I had a lot of customers get 200k out of there stock unit behind a stock truck however a lot of people start turning up the coal and then [Edited by Moparts - Family Friendly Site - Keep it clean] when the stock 48re fails. Both of my 48re's had well over 100k when I traded them and that was towing 12-15k on a regular basis.

The G56 is not a bad unit but the dual mass flywheel suck but that is an easy fix.

I would stay away from the early 6.7 but the later trucks say 2010 up are not having any where near the issues as the early ones where. And the 2013 up now us DEF so they use less EGR and are even better.

I love my new 14 it is a pulling beast with 850ft lb from the factory.