3.42 or 4.10?

4.10 if you are scared of that being too low 3.73 to get a 3.42 you should just get a half ton.

Buy the one with the 4.10 and I'll trade you mine with 3.73, if you think it is too low..

...2013 3500 Ram with the 6.7 and Aisin 6 speed...

Are they now using the Aisin tranny in the 3500? When I was shopping, it only came in the cab & chassis. I still have the Chrysler tranny.

If I were to buy a 2013 3500 Ram with the 6.7 and Aisin 6 speed it would be the 3:42. The 6.7 has more than enough low rpm torque to handle the 3:42 and you will enjoy the truck at light loads on the freeway with the 3:42. I am sure in the upcoming hill climb tests Ram will supply the 3:42 rear end and should be able to keep up with the Ford and Chevy with that combination. If they supply the 4:10 then I predict they will get their b&*ts kicked again.

e.g.,
It depends on how often you tow;/haul those big loads. I have 3.55's and it is great if I have no load on. 18mpg. and I can drive all day at 75, no sweat. With the Lance Lite on (2700 lbs. loaded), I get get 14-15 mpg. 63 mph feels good. That plus pulling my jeep on trailer, I get 12-14 mpg, and I drive slower than my 6th gear likes to run. With that GCVW of 16,000 lbs. I would be very happy to have 4.10's. If you keep your speed down, 4.10's are fine. 58 mph with a full load. If you must drive fast or have a heavy stupid pedal foot, opt for the 3.45's
The other part of the equasion is what size tires are you going to wind up with? If you EVER are going to use taller tires, opt for the 4.10's.
Generally, the most fuel efficient ratio is the lower numerical ratio: 3.45.
3.73 has been a great in-be-tween ratio that works with a load or no.
Are those the ONLY choices you have?
You thought it would be an easy choice, did you?
You will get a divergent set of opinions on this.
regards, as always jefe

Isn't the 3:73 available? My buddy has an 04 with a lance plus a trailer and gets about 13 to 14. Empty he is about 20. I have the 4:10, but it is overkill most of the time and if I had a choice it would be the 3:73.

Get the 4.10. Been pullng with my Cummins dually 4.10 rear end since 2007. If i attempt to run at 70+ empty the fuel economy sucks the big one. However towing my 13,500 pound fiver I can run all day with the cruise control on and still return 12.5 MPG.