5th or 6th gear?

[OggyOggy]

I have a 2012 4x4 2500 SRW w/ 6.7 HO Cummins and my 3.73 are useless(?). Which of course begs the definition of "useless". I tow a 12,500lb Montana at 60mph because I'm most comfortable at that speed with no desire to go faster. I have a Edge Insight to monitor all my temps and the only thing I don't like is that on slight inclines I see the post turbine exhaust temp climb to just over 900 degrees. In those cases I down shift to 5th the RPM increases to around 1,900 and the temps drop like a rock to 700ish and a slight decrease in MPG.

 

[Cummins12V98]

OK, I "GIVE" !!!

I should not have said 3.73's are "USELESS".

I should say they are not "needed" in the 2013 and up Dually trucks with Aisin. 3.42's are good for up to 27K combined or so towing in 5th with heavier loads and 4.10's will handle the rest.

Of course this is my OPINION and based on towing HEAVY with both 68RFE and Aisin trans.