...trail what is that from? Underneith where the drive shaft goes in to the back and right beside the Front drive shaft i think its the transmission but when im trying to climb a rock or go up a steep hill on the trails in 4WD it starts to smoke a lil and smells like burning plastic or somthing. but when i put it back in 2WD it goes away? i have a 1998 jeep wrangler sahara. any suggestions?