Depending on what you put it in, you need to get rid of and add certain things. There isnt really much of a difference at all. Clearances should be looser for boats considering they spend more time at higher rpm's. But you no longer need a water pump if its on a jet, so that goes, you need water cooled exhaust, so that should be on there. A larger oil pan is a must for boats as well as a rear pickup. Most smog equipment it gone. Marine carb, which is not neccesary, but strongly recomended as well as a marine fuel pump, if its mechanical. Other will chime in on this, but as long as that puppy runs, dont worry too much about it.