I have no idea why anyone would pay the same for a used truck if they could get the exact same truck new for the same price. It does not make sense. Maybe the used trucks are loaded and have a ton of after market parts and the new trucks are basic models. That would make some sense.
Do not let anyone "scare you" about DEF or smog gear. I heard all kinds of **** about my 2011 RAM 3500.
I never had it to the dealer even once. I never got an idiot light or a single message telling me anything bad, etc. I hauled my fiver to the west coast and back and over the Rockies twice. ZERO issues. Tons of power and I love the exhaust brake. My 2016 is even better......The new ones are awesome. In my area a new crew cab, 4x4 can be had for about 48 after dealing and rebates. If you have a EIN from a business you can shave a few thousand more.