Best older Dodge pickup for daily use?

What's cold?

Cummins are the most cold weather friendly of all the diesels because they don't use oil to fire the injectors. They are a common rail design.

I've been -12 cold start, no plug in, no issues...

If everything is working properly there won't be a problem. No different than a gas engine.

Northeast Ohio cold. "Normal" winters it doesn't go below zero, but it does happen. Last year was particularly colder and from the summer we had I expect about the same.

I have a friend who drives a Ford E450 Ambulance (for football tailgating) and he has to keep an engine block heater on it the night before come December cold nights. Now is that apples to apples with Cummins diesel? I don't know I'm even drawing a blank on what motor his Ford even has, just know it's a diesel. And I've heard this from others I know with diesels, but again typically Fords.