AN Adapter Fittings

The heck are you doing on a cooler that results in 1/2 NPT?? If you don't HAVE to have aluminum, you have any kind of tractor/ hydraulic hose shop locally? Tractor hydraulics, unless metric, are usually steel, and pipe, O-ring boss and JIC which are the same fittings as AN

SAE is 45* typically brass. But JIC / AN are same stuff