So this is a poor design in the first case. Not having a center support in the back almost guarantees a failure there eventually. I kludged together a support in my original more than a year ago, but finally the part broke too bad to limp along with anymore.
This is the part I needed. That being said, be very attentive about the fact that it's not the entire shelf assembly.
There is a metal support across the front of the frame that is not included. The trim above the drawers, and the humidity control sliders, are also not included. With a little finagling, I was able to remove these from the broken unit & install them on the new one, but it was a non-trivial amount of work to do so.
I also built a wooden reinforcement inside the back center of the frame at the previous point of failure in hopes that this part will outlive the rest of the frig & I won't ever have to mess with it again.