5.3 intake manifold?

First you would really want to use the LSXrt, the "t" is for truck. But its really made the the 6.0. It will take away from your bottom end power. The other LSXr manifold also makes power in the upper rpm range, plus you would have to make mods to your a/c bracket. Keep in mind that the truck manifold is made for bottom end torque which is what you want in a daily street driver. The 4.8, 5.3 and 6.0 all use the SAME intake and exhaust manifolds so if they flow enough air for the 6.0 it will flow more than enough air for a basiclly stock4.8 and 5.3 motor. Hope this info helps. Unless you building a motor with new heads, cam, bored and stroked, headers etc.. you don't need a new manifold. Those aftermarket maniflods are expension, you can do a cam change for less money and I'm sure you will be happier with the cam results. Just don't over cam the engine.