Near as I could measure, the transom is 10 degrees. I used the right angle method to locate the X dimension at 13 9/16 inches. I modified a sheetrock square to make the tool shown by Mercruiser for making the measurement. After I located the X dimension with the tool, I double checked it using the tape measure method with 13 15/16 inches recommended by Mercruiser for a 10 degree transom angle. It was right on... Next up is to drill the two 1/4 inch pilot holes with a hole saw for the relief area for the steering arm.... And then....the really fun part part, cutting the actual hole... Trying to decide the best jig saw blades for cutting it...