Does your truck have a limited slip rear differential? Did you replace the fluid lately?
When you say 'roughness', are you referring to the feel in the steering wheel? Or something shaking the body?
Did you notice the 'roughness' before you replaced the hubs? Why did you replace the hubs, did you have a bearing go out? Generally speaking, if the hubs are SO bad of condition that the vehicle exhibits 'roughness', they have to be REAL bad. And they'd be making noise too.
What new hubs did you put on? Did you put a dial indicator on the new rotors after you installed them, to ensure they are running 'true'? Because it's possible either, A) the hubs you put on aren't true (meaning the rotors will be off). I bought a hub from OReillys this summer and it was off .005" at the hub face!! That's a lot. No way you'd get a hub to be true with that. or B) The rotors might not be running 'true'. That could possibly cause some roughness. But then if they weren't running 'true', you would probably feel it when you press the brake pedal aat highway speeds.