I have a 3/4 ton Chevy Diesel and 1 ton Ford Diesel. I often exceed the capacity/ rating. Much of it has to do with terrain and excellent trailer brakes. There are hills in this area but not extreme grades. For me it is not a matter or pulling but rather a matter of stopping. You are pretty much dealing with electric brake systems and I have blown fuses. Granbury, TX is the worst in the world for people pulling right out in front of me when I am loaded (or unloaded). Good tires and good brake systems are a must. When I have a 30,000 load to pull, I make sure I pull it when I can avoid traffic and when I can creep along at about 50 MPH.
The front end on Chevy and Ford trucks have both held up well for me. Dodge didn't make it 30K. Diesel engines are heavy. When you are pulling miles across leases with a 20,000 pound Caterpillar or backhoe on a 5,000 pound trailer, you are often rendered having to pull hard across rough terrain in order to make it up hills etc. If you creep along, you are going to spin out and ruin some expensive tires. Pulling fast is hard on suspensions. If I were just pulling on mild terrain, I'd buy a Dodge, since they are much cheaper. I'll never buy another one based on my particlular needs and it has nothing to do with pulling capacity but rather where I pull.
There is a huge difference between pulling loads across pastures and pulling on pavement. None of the trucks have heavy enough receiver hitches for me. The first thing I do when I buy a truck is add and heavier category receiver hitch. Again, if I were just pulling on pavement, the factory receivers may be okay.
So when you look at the ratings, you have to consider where you are going to be working that vehicle. Pretty much all the diesel trucks have enough H.P and transmission to pull way more than the vendor ratings on flat ground and pavement, if you have enough trailer to carry the load.