Any issues with a 2015 Ram 2500 Diesel

[MarkEHansen]

My brother is about to replace his current truck with a 2015 Ram 2500 Diesel, and I have a couple questions.

First, was there a choice of automatic transmission that year when pairing with the diesel engine? If so, is there any reason to stay away from any of them?

Did the 2015 year diesel still use DEF? I like DEF due to what it does for the exhaust.

I've run the payload (and other numbers) with him and his current trailer will be fine so I think it's a good choice otherwise.

Thanks for any feedback.