You can use a heavy duty coat hanger to cut a wire out of. Buy a 3/8" dia screen door spring and cut off about 6" of it and bend a loop on that end. Bend a hook on one end of the wire and lay on the floor under the Jeep. Look for a bracket with a hole in it on the bottom of the tub behind the parking brake. When you find it hook the spring on the parking brake lever and pull the wire back to put tension on it. When you think it's tight enough mark it and bend a hook in it, cut the excess off and hook it into the hole in the bracket.
Go Jeeping.