jeffbeck,
I have a '94 JGC with a leak from the liftgate area also. It seems that water finds it way through and leaks from the vents at the top on the inside in the back. It has been doing it for a few years. It doesn't appear that it is leaking around the hinge area or the rubber. I have been letting it go as I don't even know where to start. Maybe someone else reading this thread may be able to help.