I think the official method to look for leaking seals is to use a smoke machine. I'd try something like that for leaks. Might be worth checking the tailgate for excessive movement in the hinges as well.
Lives in garage:
2004 Red Jeep TJ "X", big tires, suspension, stereo delete, dent in cowl.
1982 Red Jeep Scrambler, small block chevy on 35's.
"Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." -Benjamin Franklin