Hey. So my car was in an accident before I got it. The body work was less than great. Five years later, I had to buy and install the omitted gasket for the tail-lights. That alone didn't stop the leaking, so I caulked them too, and the leaking stopped for a while. There's water getting into the trunk somehow, and I suspect it's from the tail-lights again because of what's wet.

Anyway, there are about 50 kinds of caulk to choose from. I was advised that silicone caulk sucks and should be avoided. I'm inclined to agree.
I saw some construction adhesive, but I don't want to glue anything to anything. I want to replace the passenger taillight at some point.
I also saw some for flashing and gutters that looks like it should adhere to metal and plastic. There was also some that said it would adhere to metal, fiberglass, and so on.

At this point, I'd even consider some of that expanding foam sealant, if it would stop the leak.

Happy Bricking! (this is a 90 740T if anyone cares)