On the larger (40/50HP) the port is a screw hole on the side of the lower unit. But you likely don't need to use it or the special fitting, if the water inlets are on the side of the lower unit then regular old muffs will probably work fine. My 50HP has the special flush port, but I've been using muffs with it for the past 20 years without issue. Just make sure there is sufficient water flow to flood the pump.
