Oil leak with 430k miles

Hey guys,

On my most recent roadtrip I noticed I was losing an alarming amount of oil, something like 1 quart every 200 miles. I made sure it was topped off until I got home. I picked up some dino 10w40 (normally run 5w30 Mobil1 synthetic) at a convenience store and that slowed the leak down enough.

I didn't think that much oil could possibly all be making it to the combustion chamber without blue smoke, a mileage hit, codes, etc. Sure enough, I found oil dripping underneath. It's biased to the driver side, and in particular I see a lot on the tranmission cooler lines and behind. I cleaned it up with brake cleaner and it all came back after a short drive. Pics below.

However, for the life of me I can't find a plausible source here while poking around with my flashlight. Any likely culprits come to mind? This may just be above my skill level.

Other potentially relevant info:
-'08. V6 4L. 4x4.
-Headgasket done by dealer about 100k back (coolant was getting in).
-The old girl's been burning oil at a reasonable rate for her age, probably 1 quart per oil change (about 3K miles) since around 300k. I normally just check the oil when I fill up on gas and top it off if necessary.
-I replaced the PCV valve with the last oil change, hoping that it would fix the gradual oil burn.

Please help me get my baby to 500k!

 

Before I saw the pictures, just thinking of what could be that much of a gusher... I'm thinking either harmonic balancer seal or rear main.
Based on your pictures... I don't know.
Those two might be a good place to start or get some dye and a UV light.

 

Have you had the truck since new, if not could there be an aftermarket engine oil cooler? Start the truck and let it idle, look around to see if you can see any oil dripping or spraying.