With recommendations from the guys here, I found my NEW, at the time, December 2006 built, 2007, 5.9, 4x4, with the 6.7, G-56, 6 speed because Dodge ran out of the G-56 for the 5.9's. I now have 110,000 miles on the truck and it has been a very trouble free, wonderful towing and nice riding truck. My wife drives the truck towing the 5th wheel we own because the G-56 is a very easy shifting trans. DON'T put a 3" lift kit on it, (My Opinion), maybe the front leveling kit. I have also the free spin hubs and it makes a big difference in the lightness of the steering. The hubs make it nice to have 2WD-LOW range for backing trailers, especially with the stick shift. My truck has the MANUAL HIGH-LOW shifter. I have read here about some issues with the "Dash" electrically shifted transfer case.
I added a PacBrake PRXB not long after I bought it and other than wearing out the compressor, It Too has been trouble free. In my Opinion, while the 48RE is a great transmission, the gap between third (direct) and the .69 OD which is 4th gear makes it not the best for towing or over sized tires. My steering at 110,000 miles is great. I can go down the freeway and take my hands off of the wheel and the truck goes straight. I run 285-75-17's and it makes it nice empty to light towing. To get the right gearing, I put a set of stock 265-70-17 back on if I am going on a long trip with the 5th wheel. Actually the early G-56 trans with it's lower geared OD(6th) would be perfect for O.S. Tires.
Weak points: 06-07 is the TIPM if it is not treated right. I made up about 30 "TIPM Savers" which took the trailer tow plug and isolated it from the TIPM. Anything I have added electrically, I didn't tie into the TIPM other than to get a signal.
'04-05, I have heard that guys aren't happy with the headlights. I added some PERLUX. 130 watt driving lights on my 2007.
I wouldn't trade my '07, 5.9 for even a brand NEW Dodge. I wouldn't mind an AISIN 6 speed automatic trans in it.