Not sure what kind you have in there now but if you plan to go to a Dexcool type of antifreeze you need to take care. If you have the regular green type, you may have trouble with gelling and plugging down the line if you do not flush the system out well. This happened to my boat. I had to take the cooling system apart and clean the gunk out. The older all cast iron diesels seem to do just fine with the old green glycol based coolants but the newer engines with lots of aluminum seem to do better with the newer stuff. I'm sure others will chip in their experiences.
Kevin