ATF leak at transmission heat exchanger - 2005 Dodge Ram2500 Cummins (3rd Gen)

I've been trying to track down the last of the ATF leaks on our 2005 Dodge Ram 2500 with the 5.9L Cummins engine.

I caught this leak in action - it's on the line between the transmission and the heat exchanger that's bolted to the block.

Ideally, the fix will only be to remove the line and fitting, clean and apply sealant, and re-tighten it.