I was looking over the engine bay of Superblack ('92 5.3) today closely for the first time after replacing the worn-out original hood struts, and noticed something that kinda stuck out weird: the crossover coolant pipe up near the firewall was chrome-plated (or possibly polished stainless steel?). I don’t think I ever noticed this “engine ornament” on any other 5.3s I had seen before. Is this stock, or did a PO for whatever reason decide to try to fancy up/customize the engine a bit? 
Paul, are you sure that you are not looking at the balance tube, close to the firewall, that connects the two intake manifolds? Those will polish nicely. I used Mother’s aluminum polish on mine.
I’ll take another look at it, but why would the 5.3 need to “balance” between the two intakes? So is that air intake going between them from the air cleaners?
Yep it is…
If you start the engine and keep your foot off the gas pedal, both throttle butterflies will be almost closed. If the engine is cold, the auxiliary air valve (the troublesome unit with a piston inside that responds to temperature) allows some air into the engine which MAY give you a slightly higher fast idle, and the balance tube lets some of that air flow to the RHS, or “A” bank of the engine. That’s the “balance” part.
Once the engine coolant warms up, the balance tube still allows airflow to the “A” bank, as the idle speed should still be controlled by the AAV, using the idle adjustment screw. (Actually a bolt.)
Hope that helps!
Seems to make sense. 
Thanks.