One more thing Cummins recmends not to let your engin slow below "peak torque" under load. You should down shift to reduse the load on your engin.
Anouther way to say it is when on a hill in cruise and it slowes down to where your engin rpm will fall below "peak torque" you should down shift to reduse the load on the engin.
One more thing I won't drive a diesel with out EGT and Boost gages.
2008 Newmar Mountain Aire
450 HP Cummins ISM 4000MH Allison Trans.
Towing a 2014 Honda CRV with a Blue Ox tow bar.