My third brake light leaked but did not stain the headliner. The vents behind the rear seats leak as well. One of mine was leaking and I replaced both with the upgraded ones from the dealer. They were about $11 Cdn each. Your roof antenna may be the cause as well as the other 2 problems and the window seals. The seal on my brake light showed clear signs of degradation and water infiltration. I replaced the whole assembly. I had my roof painted because of rust. (Nova Scotia road salt and livng next to the ocean.) Had the antenna changed at the same time although the body shop said there was no sign of leaking from there. I took out my back seats and lifted the carpets off the floor enough to let air from a couple of fans blow thru the truck. It was still time consuming and we were fortunate we have a 2nd vehicle. It took weeks to dry outside in the late winter early spring.
Here are some pics.
The vent pics are the same vent just opposite sides.
The vent part no. is 0053459891-001 or 6832 349 AB-001. Those are the nos. on the package. One of them is the stock no.
THe brake light seal failed after 8 years and I put this down to wear and tear.
I was unhappy but I just fixed it. I had an extended warranty but the dealer said they do not cover water damage. You're on your own with these problems. I have never heard or read of anyone getting this fixed under warranty or for free but there must be someone surely.
I read a description on a page selling a new upgraded seal and they said scrape the old seal off completely before applying the new one. I opted for a new assembly parlty because I didn't want to do that.
Here is the link to that page
Detroit Muscle Technologies, LLC Mopar restoration gaskets
www.detroitmuscletechnologies.com
Good luck.