I have owned my Mercury for almost 50 years, and there was some kind of insulation on the under side of my hood. The insulation was pretty much falling off, but I remember a pad with what looked like fiberglass insulation hanging from my hood when I found it in a barn in Wisconsin.
Thanks tjc. My parents bought a ’54 Mercury and I thought that I remembered exactly what you describe. I have found two sources online that have something that looks similar. It is a “cut to fit” product. Would like to find a source that has something close to the original.