The Dexter Torflex #10 axles assemblies rated at less than 3500 pounds have shorter rubber elements in them to make the springing softer and so better suited to a lighter trailer; the rest of the components are the same as if it had a 3500 pound rating. This can only be done at the factory; the buyer just orders the rating desired, in 200 pound increments if I recall correctly.
While Escape uses the Torflex #10 for all current and recent models, they are in at least three widths so even if they were all rated at 3500 pounds (and they might be, now) they're not interchangeable. It's not difficult to buy the right number of the right axles for the planned production.