I have 1997, 2 stroke, 25hp, mercury, tiller that I got with a beat very beat up prop. The prop on the motor says 48 19640 A40 13p, then lower it says 9632x. Is this the stock prop that came with the motor? I want to purchase a new oem size prop. I am happy with the performance as is but think it is unbalanced. Any other suggestions??