I am not 100% sure you can buy one and add to what you have if that one you have doesn't have one.  But I have a 2006 just like what you are talking about but with a tiller, so I would guess you should be able to put one on.  I am not sure where you are located, but I have used Auburn Sports and Marine to buy parts for mine before and they have been good about info also.  GREAT motor by the way.