Model # OB261937 1988 70 hp. Got this motor which came without a prop, I cannot find the prop for this motor on-line, even called Iboats, & 2 other websites. They give me a # for a 13 spline mine is a 15 spline. checked & re-checked. Anyone who can give me a standard RH recreational aluminum prop # ? plain middle of the road prop. thanks.