I have a recent (90's?) 8 hp Tohatsu and I see that the 9.8 of the same vinmtage has all of the same specs! My neighbor has the 9.8 and even the carb appears to be the same! The engine hoods are interchangeable! How do I make my 8 into a 9.8??????? I used to have a 2.5 ....never did find out...