AFAIK. Isuzu is the only company that sells more diesels than cummins.

I dont like the duramax because of its bore and stroke. Itll have excellent transient response time and haul butt empty. But why buy a diesel to drive it empty. I would take a na 6.9 over a duramax but thats just personal taste. Im sure the duramax is an excellent engine.

That said. An old friend of my dad has one and gets over 20 mpg. Not bad for a 6500lb pickup. Tows better than anything hes ever owned before. But then again. He has never driven a 6.0.