Crew cab headliner rattle

[D-Day]

Good God, does it ever end? My guess is no.

Anyway, I have a new sound and a new problem. Headliner rattle. It only does it at certain RPMs, like taking off mostly. I sat with it running in the driveway and banged on the pillars, and it'd cause the most vibration. My guess is some support band or something got loose or fell off and is causing the problem - however, if I put pressure on the opposite pillar of the one I hit my fist on, it won't rattle (or at least as much, as I remember); but it's not the plastic trim on the pillars themselves.

It's a tapping/rattling sound, as if large singular drops of water are falling on the roof in rapid succession, or a nickel is on the roof. What exactly is in the headliner? Mine's old and sagging, so I have a feeling it may be time to replace it if this is the only way to get rid of the noise and keep the looks.

So, advice needed on two things: What is in the headliner to make this noise, and: if I need a brand new headliner for my crew cab, where can I get one?

I'd prefer one of those molded ones, easy to put up like they had in JC Whitney years ago. I don't really feel like doing the factory style setup, since I have to do it alone. The more out-of-the-box, the better.