That was exactly the rationale we used to justify buying it when we did.
2006 was the last model year with the 5.9L inline 6 Cummins engine, WITHOUT all the next-gen exhaust nonsense and DEF and so on. Just add fuel and go. (BTW, we get ~26 MPG in mixed driving.) Also, that same 5.9L Cummins powerplant is used in everything... boat engines, generators, construction equipment, you name it. They're everywhere, which means parts and service will be available anywhere. We've had boat yards say "Let us handle the maintenance on your truck, we know that powerplant inside and out".
Also, 2006 was during the period that Mercedes-Benz owned Chrysler. As a result, the six speed manual transmission used in that era is actually an MB transmission designed for Class 5 truck applications (up to 19,500 pounds). Our one-ton 3500 doesn't even remotely approach the design parameters of that transmission so it lives a nice, easy, comfortable life and should last basically forever.
I have zero loyalty to Dodge or any other brand. What I wanted was a hyper-reliable powertrain since that's where all the value is anyway. Research told me Cummins was the way to go, so I tell people "I bought a Cummins engine and it came wrapped in a Dodge truck".