Depending on the brand you have, we would either need your engine Serial or Model number to determine the correct stern drive.
For Mercruiser stern drives, we need the engine serial number. It will start with a Number, followed by a letter, then six numbers.
For OMC stern drives, we need the engine model number. It will be a three digit number followed by five letters. It will start with your liter capacity.
With that information we will be able to sell you the direct replacement needed.