The repro picture does give the look of fiberglass, but the part is actually cushy.
This survivor pic is a better illustration.
You can see the worn edge exposing the fluffyness.
Do you agree it looks akin to Mustang in construction?
Wouldn't surprise me if originals had asbestos in them, so any repro is going to be different without it.
They weren't just sound deadener, they were to smother fire too.
Didn't work as well with metal retainer clips though.
They were changed to plastic in 66 so a fire would melt them and allow the blanket to fall and form right around the motor to be more effective.