I found my problem, like others BOTH tailights are leaking. I fixed the pass side with a generous portion of RTV silicone. It is very cold here in the midwest so I am waiting to re-do and re-test the drivers side when it gets above freezing.
This is a simple fix to a real problem. I think because the prior owners had a wreck in the rear (I found masking tape on the inner fender aroung the black vent) the tailights were off a bit. In my car you need to jam the tail lights outward away from the middle then tighten the screws (the holes are slotted)
. Just a little tiny gap will let in lots of water!
