I have recently bought a 2002 ford explorer 4x4.It came with a class 2 hitch that seems to be part of the bumper.It has bumper stops on it and its shaped the same as the bumper.what i need help with here is how can i get a class 3 hitch to put on it and is it possible.i installed many of these reciever hitches but this 1 is really throwing me.