Let me add to the 68RFE argument.....I bought a 2012 MAX tow dually 30K GCVW with the 68 RFE/4:10. The transmission shifted just like it should, no flare, slip slop hip hop shifting etc..... Then I bought the 2013 RAM with the EXACT same drivetrain(except 3:42's) expecting similar results.....The 68 RFE in my opinion is miss slip slop, hip hop flare shift-a-rama mess compared to the 2012 68 RFE. Previous 68 RFE's to 2013 do not have the slip slop flare that the 2013 and ups apparently do. ( Like I said recently, "Carlos from DELL tech support" must have reprogrammed the shifting pattern.) I've been told several times over the last 14 months "Carlos" was putting out a re-flash but this has not happened.
I had the ABSOLUTE pleasure of driving a Aisin transmission in a 2014 RAM recently and it was awesome...If anyone buying a new RAM has the extra few bucks it takes to buy the 3500 with a Aisin, do it....You wont regret it... Mine does the job, but ASAP shes' going away and I will have a nice shifting auto (Aisin) once again.JMHO from actual experience.