Leaking Tranny Fluid and can't find the leak?

[SubVet]

Ok, my truck is a 99 F250 (1/99 build) with an auto and it is leaking transmission fluid. The fluid is mostly dripping off of the passenger side rear shackle.

I noticed a few spots the other day on the driveway. I haven’t used the since I noticed the spots. The trans temps have been relatively cool. They don’t get above 165, I haven’t done any towing or hard driving with it.

It starts dripping within 30 seconds of starting the truck. Like I said before, the shackle is wet, the frame is wet (about a 6” area around the shackle), but I can’t see or feel where it coming from. I ran my hands on the cooler lines but I can’t find a leak. Any ideas, thoughts?