atwood G6A-8E water heater leaking at cold fitting

It could be the threaded fitting going into the tank. Some rigs have a plastic nipple and some have a plastic check valve.

Many a leak can start from the pressure release valve too. It's only a ten dollar fix and might be worth it for an easy fix. It could leak all the way down to the inlet inside the insulation.

Is it an electric/gas model?

Put a paper towel around the fitting where you suspect it is coming from, and put the pressure to it for just a short time. You will notice the wetness on the towel before you will see the drips if it is coming from there.

I had a cracked plex fiting that attched to the nipple from the tank.

Thanks for all your suggestions.
My tank has a metal nipple. A brass fitting attaches to that and a brass female end attaches to that. The hose is plastic and is crimped to the brass female end. Very old school.

The crimp is solid, the female is tight to the brass elbow fitting, and that's as far as I've gotten with my exploration. The cardboard and insulation around the tank was all wet, and I couldn't really assess the metal nipple at the tank. Lots of calcium type buildup around that nipple as well. I will do more exploring tomorrow. It's a very tight squeeze under the coach, with little wiggle room to play with tools....

Oh, and the pressure release valve seems fine. It is at the front of the unit, and there is no moisture around the pressure release valve where it screws into the heater... Can it leak behind the front panel?

I am not sure what kind of end fitting you have and how it is suppose to seal but if it is not a flare or bubble end maybe some Teflon tape would seal it. I would remove it and see.