So, I forgot to update. They replaced the wiper cowl a week ago...and...it wasn't the problem. Squeak is still present.
The next thing they're going to try is resealing the windshield. Hopefully that fixes it. I'm just waiting for their bodyshop to tell me the parts are in.
So, if you recall, last winter I complained that there was a squeak where the dashboard meets the passenger A-Pillar. The dealership had a look at it, replaced the wiper cowl, and resealed the windshield, to no avail. The squeak remained.
The next step would be to start tearing into the dash to find the culprit, but I wasn't sure I wanted them to start doing that. Tearing a dashboard apart is pretty drastic, and I'm pretty sure it would never go back together like it should. I was already prepared to just live with it.
Then this weekend, at my work Xmas party, I'm talking to a couple of managers from our store who both drive Tundras, a '16 and a '17, so the same generation as mine. We were talking about Tundras (fuel economy was a common theme, lol), and one of them asked if I have the Dashboard squeak near the A-Pillar. It turns out that all 3 of our trucks have the exact same squeak in the exact same location. So I guess it's just something that these trucks do. It makes me feel a little better that my particular Tundra isn't screwed together any differently than any other Tundra.
It's a pain in the ass, but I guess I"m just prepared to live with it from now on. It really only happens when it's really cold out, the rest of the time it's fine.