yes. if you have a 3/8 inch rear axle I would suggest buying a hub with the same size rear axle.
you can buy a 14mm axle hub but you may have to file the dropouts out on your frame and if you don't know what your doing you will be buying a new frame.
you are aware of the 'play' or slack that a freecoaster has, right?
that is, when you try to pedal forward after pedaling backwards, even if your rolling forward, your pedals will not engage until the pedals go about 1/2 way around.
unlike the freewheel you have now, there is play in the freecoaster hubs. you can try and remove it but most people end up with more then they really want unless they ride flat exclusively.