Has anyone removed the original smog tube from the exhaust manifold from a 1970-71 Z28? Do you know the length of the pipe insert? The GM pipe insert is 3 1/8" long. Years ago I had an auto shop Install my original exhaust manifolds and the smog tubes. I supplied the GM pipes for the tubes. When I removed the smog tubes and the pipes recently they were less than 2” long. I’m not sure if the auto shop cut them down or something else changed the length. Any information would be greatly appreciated.