If you are towing something that is close to your limit, or even a bit over (as most of us do lol) depending on how many miles are on your truck you might want to consider changing your rear diff fluid somewhere in there, depending of course on the proximity of an interval.
The only reason I suggest this is I have always noticed that the paint starts peeling on my rear diff covers in these trucks (this is my fourth, one second gen, two third gen, all HD CTD though, this is my first 1/2 ton) from the heat. That always made me worry a bit, but i never ended up with a problem, and I would regularly exceed 26k lbs combined weight. I am considering a vaned aluminum diff cover that increases my reservoir size slightly, but since I don't push the 1/2 ton as hard, I am undecided on whether or not it will be an issue.
The fact that it's not a posi is better in this case anyway too as the wear of the clutch packs won't leave any extra sediment in the fluid.
Point is, you are probably fine, trucks are designed for tow/hauling, but it never hurts to know what your fluids look like.
