My 04 TJ’s radiator has a leak at the bottom. I hear MOPAR is the best but I haven’t been able to find one. What aftermarket brands are people using and recommended?
Denso is a good quality replacement. Widen your search to include those for automatic transmissions which only include a couple extra fittings at the bottom for use by an automatic. They work just as well for those with manual transmissions. Their bottom transmission core is completely separate from the radiator core so its ports don't need to be capped off except maybe to keep the bugs out.