there is a petcock
Chuck, there is a petcock under the air intake side of thte 25XP. You can fit a short piece of plastic tube over the petcock outlet. Then the tube can be drained to a low point, ie a coffee can in the bilge. Open the radiator cap and let it flow. You may have some coolant trapped in the water heater, so blow that out or disconnect the water heater hoses under the aft galley drawers. Remember that radiator caps wear out so consider a replacement. I just completed this task including a flush. If you do the flush use a Prestone type of Radiator cooling system flush and an auto store flush and fill kit and follow directions. You must disconnect the hot water heater since it is aluminum. I hooked up a short hose off the auto store flush and fill kit at the radiator cap outlet. Used a Y garden hose fitting, one side to fill the bucket one side to the kit inlet to flush the cooling system Once it is just water you can run it into the bilge. If you run the engine on the hard do not hook a hose up to the Oberdorfer inlet. Let the oberdorfer suck out of a bucket and run the hose into that bucket. This atmospheric break is essential to avoid filling the cylinders with water via the exhaust system. Good luck.
