06 truck water leak

Been searching for awhile to find the leak that fills up the well under the fold up back seat. Sealed the third light, nope, sealed shut the sliding back glass, nope.
Water was coming in around that stupid black antenna thing on the roof. Two big rains and no leak so far. I would love to remove it completely, useless pos.

I believe that is an antenna for SiriusXM. I also have an 06 with the same antenna, but never had a problem with leaks in it or the 07 I had before it. But then again, I live in the driest state in the country.