I watched this Leno video because of him driving a '69 Z28 and wanted to see what it looked like. It is a nice story but the owner did not appear to know much technically about the car. When I heard the driving video, it was immediately clear there was something wrong with the exhaust! Seeing the blown muffler along the seam explains the noise...and very odd. And yes, I have never see a stenciled part number on an original exhaust system muffler or resonator.