Dana 60 axles are commonly used here for three-quarter ton trucks (Ram 2500, Ford 250, etc), and for making a USDM NPR into an NPS. That axle is rated by Dana from 4500 - 7500 pounds depending on hubs, brakes, wheels, tires, gear ratio, width, etc.
3100 kg = <6900 pounds. So, you would need a Super 60, a.k.a. Fat Boy, from a Ford F450, to exceed this factory weight rating (GAWR), or to purchase an axle from a third party, such as Fusion, Currie or Dynatrac, which I suggest avoiding at all costs. As many of these axles are built for custom applications, such as off road buggies and Jeeps being converted from half-ton parts to one-ton running gear, the OEM rating isn't often shared, as it would be if that axle came on a new F-350 pickup truck. I don't imagine the axle would fail with a bit of extra load on it, but having a stronger axle is never a bad thing, especially if you are doing tough tracks or travelling in remote areas.
Other options are to get a Dana 70, Dana 80 or even a steering 14 bolt from a company such a Crane Axle in Tennessee or Torq14 in Utah (I think).
Do you have the specs on the axle that is being install under the front of your truck?