You can - and I do - make more HP and torque than any of those trucks even with 20 year old diesels and the right parts. You can also build the transmission to handle it. So a new Ford makes 440 HP... it will still be embarrassed by a 20 year old truck with the right mods.
And the new ones can be tweaked for even more too. My point here is you can have however much power you want in whatever truck you want.
The real reason you don't see Duramax competing in the max tow rating race like Ford and Ram is that almost no one tows that heavy!
How many of you have a 30,000 pound trailer? You'd need a CDL just to drive a pickup with a 20,000 pound trailer behind it. Do they even make a 5th wheel RV that weighs more than a Duramax can handle?
The only thing that weighs anywhere near 30,000 is a gooseneck equipment trailer and unless you have one of those AND a CDL, the Chevy is more than plenty.
I'm not favoring the Chevy, I'm just saying, the one with the least tow rating (Chevy) is already more than enough. The Ford and Ram are just in a bragging rights race that has gotten beyond what we can even use.
If I were buying a new truck today I don't know which I'd go with. All three are pretty awesome. Unfortunately all three are way, way too expensive. I agree with the others who said they have better ways to use $80,000!!
RVs are fun, but so is flying to tropical islands.