Well the orig prop i assume its the orig cause its color matches the motor. Any way it has a nice chip in a fin so the prev owner replaced it with a new one from michigan and they are different. Looking in my parts manuel i can pick from like 4 or 5 props it says, and im assuming the new prop is one of them but im getting poor gas mileage and would like to mabey try a new prop. Is this going to effect gas mileage? I dont have a tach to see the rpms is there mabey another way to test the prop? My orig prop is a 10 1/4 x 10 and when i look up a prop if this size it list it for up to a 35hp motor. Now when i look up a prop here the only one aval to me is a 11 x 10. Which is not in my list for props. I get a 9 1/2 x 10, 10 x 11, 10 x 12, 10 1/4 x 10, and 10 x 9 1/4.