It could be leaking from the water pump. There is a small hole in the bottom of water pumps that will leak coolant when the bearing id going out. This is so you have an indication of failure before it comes apart and destroys other engine parts.
Mixing the new red antifreeze with the green can cause it to look rusty and will form a sludge. If someone is topping off your antifreeze recovery tank during oil changes with the wrong product could be one cause.
Antifreeze leak in a 1999 Jeep may be as a result of a defective water pump or a cracked engine block. Antifreeze leak in your 1999 Jeep could be as a result of a radiator fluid leak, a cracked engine block, a defective water pump, or any other reason.