@The HOFF . Your original truck was way over ratings...possibly over capacities as well.
In the pic thread another member has a very similar 5th wheel and a 3500 dually. Take a look at that and maybe ask him a question or too.
Also we have a personal message setup for talking one on one with some one.
If I were you, I would get the air suspension and 4.10 from your other questions. Your air suspension failed from all the right things met at all the right times. Your other 2016 truck, luckily never met all those conditions at exactly the right time, it was well overloaded as well.
I would also get the HO Cummins...that is a huge home on wheels you are towing.
I broke down the numbers for your other trucks, we can do that with a new one too.
Good luck with your purchase and hauling/towing in the future.