I was in the same boat as you....2010 3500, 68rfe,373's..but mine was a crew cab..did some research and bought a 2014 3500 crew cab with the HO 6.7,Aisen tranny, and 410's. Now when I upgrade my 5er I have more than enough truck. But I traded my old 3500 and my wife's 1500 in on the new 3500 and a new 1500 for her and it only cost me 80 bucks a month more than just the old 3500,,her 1500 was paid off,,but I did do alot of shopping and dealing to come out where I ended up I think luck was on my side as well....you can find one it just takes some work to get it done.
Oh and by the way the new one pulls so much harder than the old one...I feel you can't go wrong with the drive train that I found. If you love ram's you'll love that combo.