Coolant leaking on back side of motor

[kevinator]

I have a 2004 F350 6.0litre, I get a pool of coolant under the truck when it sits for awhile without being started. It doesn't seem to leak while it is running.I crawled underneath and it seems to be coming from the drivers side,up on the very top corner of the head, it then runs down the motor,onto the bell housing and then drips on the ground.Truck runs fine and dont notice a difference in the coolant reservoir,about 3/4" below the min. mark. I did notice however a chalky white substance around the reservoir cap on the reservoir, where it came from i have no idea.
Any thoughts would be helpful and appreciated!!

[pa444]

you could check the oil cooler to egr cooler hose its a short orange (old style) or blue (updated) hose. if you look on the top of the engine in the valley near the left head under the turbo pedistal. its known for leaking especially if its the orange one. would help to if you could pressure test the system cold and hot while your looking around. coolant resivor also known for cracking on the bottom causing leak. couple things to rule out if anything.