1993 Jeep Laredo electrical fault/ major drain

My 93 Jeep grand cherokee 5.2 ltr V8 keeps shorting out the battery or has a short some where that keeps draining the battery when powered off. The battery reads about a constant 13.5 or higher drop when powered off with a volt meter. New alternator, new water pump. But has always had this problem from the point I first bought it. I tried everything to my knowledge so far but as I can tell the short is coming from the fuse box but I can't tell which component it is. I really need help on this one.