One of our guys has a 2017 that setup. had transmission problems since new.
Recently they finally put a new transmission in it. Still has issues. Hauling 140,000 lbs.
I think the older model DT-12 wasn’t rated for this heavy use.
They now have a heavy duty DT-12 rated to 250,000 lbs with a crawler gear. That may be a better option.
The engine is pretty solid. I have a 2016 DD16 600/1850 in Cascadia. I had a 4900SF Western Star. The Star is a way more solid truck than the Cascadia.
There’s three of us with this engine. Only real issues has been emissions faults. Nothing debilitating, but aggravating nonetheless.
Pulls good, engine brake is awesome. Had a DD15 before, the engine brake is way stronger on the 16 litre.