Hey TPC,
From what I researched the Hemi comes with the 45RFE which is the 5 speed auto. Its in the Durangos and 1/2 ton p/u's and if I'm not mistaken the 2500 gassers. The 48RE is in 2500 and 3500 only from what I hear and I don't think you can get it with gas motors because its only a 4-speed and the trucks have to pass some bullshit fuel usage standars so they use the 5 speed auto. The 47 has been discontinued and was replaced by the 48. They are both 4-speed autos.
My Durango had 36k miles on it driving the mountains, pulling my boat, and pulling my 19' travel trailer. Both the boat and the trailer pushed the limits of the tow capacity for that truck. We never had a problem with it. The problem with the trucks is that the Hemi has about 100 more HP that the 4.7.
I wouldn't worry though, because it comes with a 7/70 powertrain. My local Dodge dealer has been great to me on warranty work on my Jeep. But the first dealer I went to was crooked. You just have to try a few out to find a good service department.
OL