The shallow wall that we suspected is not weight-bearing, better not be... since 2 of the 3 studs have huge chunks cut out of them.
Here's a closer look...
The missing chunks had nothing to do with the current (now, most recent) install. So either this was scrap wood used during the initial build or the most recent install was not the original install.
The cabinet has been saved for later use and a few other things have been saved to go to the local Re-Store once we're finished.
We thought we were going to have a big issue with the standard tub length being 60-inches, because our tub measured 58-inches, installed. It turns out to have been built into the wall... the old tub was also 60-inches. So there was some creative sheet-rocking going on.
Next step is to fit the new tub. :-)