Sorry but there was lead wool in aft overhead of the early aircraft. I saw them putting it in at Palmdale in 1972 and 1973. Came out later with improvements.
You can be "sorry" all you want, but I worked on the production line from 1970 (s/n 1001) to 1977 (s/n 1145) when I became a training instructor, in 1982 I went in to product support and worked there until I retired. All that time the insulation batts were made of spun fiberglass with tedlar covering, no lead wool.
Also, air cycles sounded like muted police sirens in early aircraft. The finally put in tuned mounts for them.
They sounded like unmuted police sirens on the late aircraft. But, you expect that from something spinning 28,000 RPM.