I ordered a new prop for my 1969 650E (4 cylinder) and when it arrived, it was too small. When I called the prop shop and told them my prop shaft was 15 spline instead of 13 spline (what they gave me) they checked with the manufacturer who insists 15 spline is a Mercruiser I/O prop shaft. Is it possible my prop shaft (or whole lower unit) is from an I/O? Or are the prop people wrong? They're exchanging it for me regardless.
