Depends on what axle? It would have to be a damn old, and odd axle to not be able to put brakes on it any way. I converted a set of mobile home axles that didn't have brakes with TSC stuff. If it has a standard style spindle, the most you will have to do is weld on the flange.
I have yet to see a normal 3500 pound axle not be able to take a set of brakes.