White smoke could be power steering fluid or automatic transmission fluid burning off on the exhaust, or it could be exhaust leaking out and cooking the fluid or just a little engine oil from the valve cover. The logical suspects are the power steering hoses, the transmission cooler hoses that attach to the radiator bottom cap, and unfortunately the stock exhaust manifold.
Check the hoses first and hopefully that is it, the manifold is a pain to change. If you have an oil leak from the valve cover, that's not too hard to fix either, by fitting a new gasket.
The stock exhaust manifolds are actually more durable than any aftermaket headers, once Jeep started making them with flex joints built in. They are actually cast iron shorty headers. Don't make the mistake of buying any stainless steel headers without the flex joint, they cost a lot more and last a lot less.
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