Replaced water pump put back together still leaking looks like it's coming from behind the alternator filled it up when job was done didn't even have to start it and it was leaking out?

 

Is that anywhere near your thermostat housing? They can crack and spray a leak backwards towards the back of the engine.

 

On my 2004 4.0L SOHC I had a crack in the coolant hose that comes out of the bottom of the thermostat housing. covered the passenger side of my engine under the intake with coolant. I'd try looking there or along the hose that goes from the housing to the radiator for a pin-hole leak

 

The SOHC also has an 90 degree elbow heater hose that comes out of the block on the passenger side. It is a common failure point. I just had to replace mine after it blew. It is under the top radiator hose.

 

Thanks for the posts on V6~4.0L~SOHC engines & TStat housings; good reference info.
Replaced the old leaking FRPlastic TStat Housing with a new Aluminum TStat Housing
in 2019Aug on a 2001 Ford ExSportTrac; no leaks as of 2020Mar after ~5K more miles.
My full write up with pics on that repair:
http://2001fordexplorersporttrac.fandom.com/Coolant_ThermoStat_Housing