Choosing the right truck.

Yes both run DEF

 

Very good!

 

Volvo dealership I went to had software that took the specks of the truck as you were ordering it, when we got to the gearing we played a lot with it trying different rear end ratio, wheel size, tires and so on. It is pretty amazing the results it shows as it will give you all the demographics from MPG to speed, startability and probably 20 other things!
I also broke down all the possibilities matching a Cummins and eaton fuller, that took a while to get all the info from Cummins and Eaton and then matching them to the truck, I eventually came up with a good match but not as efficient as the Volvo combo. Surprisingly the Cummins was most fuel efficient running at 1500 to 1600 RPM vs the Volvo at 1300 to 1400 RPM but churning out more torque, think that's why the Volvo had the edge with the MPG!

 

I was working as a mechanic back in the day when those screaming 2 stroke detroits were the main engine out there.
Back then it was gallons per mile!