If you have what came from the factory, then it's referred to as exhaust manifold/s. If you're like 90 % of individuals, you rarely see above 3500 rpm which is the starting point of where headers become beneficial. The stock manifolds are fine for engine speeds below 4000 rpm. Look at wrecking yards for a used set. If you can't find a Jeep to pull from, then look for AMC autos w/V-8's as they should be the same. If no luck, try calling Specialty Parts in CA at 800-504-5337.