Answer
They can be, depending on the hp rating, or in board , outboard motor, what you need to do is go to your local mercury/mercruiser dealer and ask them, murcury has bloke
uals and parts interchange catalogs at most locations,
you need to let them know the year make and model of engine ( example: 74 mercury 15 hp outboard ) you might need a vin# also this will help with finding an exact mach for you usually located on a metal tag on the tilt tube/steering pivot of an out board and on the carb. cowling on an inboard