Rear seat floorboard passenger side has no drain on my 99, can I put one there without messing anything up? All I can see looking from the underside is the muffler. I am doing away with carpet and covering with Bedliner.
There are drains there already, they're just sealed from the factory for some unknown reason. They're oval. I used a sharp wood chisel to remove the putty/sealer and then the metal plug pops right out. It's not designed to be removable, so you'll need to pick up some oval drain plugs for a JK. I ordered plugs for all 4 drains off Ebay for less than 15 bucks. They work great. I recommend doing it the way I outlined rather than drilling holes in your floor. The floor is designed to drain out those holes and mine drain quickly and completely when I need them to.