Isn't the thermostat right above the water pump on our 4 litres? It could be that it is the thermostat, and it's dripping down onto the water pump giving the illusion that the pump is whats leaking.
1966 Mustang Sprint 200--Wimbledon White
1998 Mustang V6 Coupe--Silver--RIP, Totalled by brother
2005 Mustang V6 Premium Coupe--Sonic Blue