Two problems related to radiator have been reported for the 1999 Jeep Wrangler. The most recently reported issues are listed below.
Radiator made with plastic which leaks at the top where the plastic is crimped to the metal core. This is an inevitable problem on all Jeep (Chrysler products) made with radiators manufactured using plastic causing leakage before the life expectancy of the radiator is reached. In some cases, coolant is flammable. To my knowledge no recall has been performed.
52,000 on my 1999 Wrangler (have never been "off roading in it). I just replaced the radiator with an after market brand - not Jeeps radiator. I'm in the process of ordering a new exhaust manifold (mine is cracked). Once again I was advised to buy an after market manifold because the Jeep's manifold is a lesser quality. It has been explained to me that both of these repairs are frequent on this model and should be a factory recall.