Yep, plastic. And the motor shaft is made out of a softer material so set screws now bite in and loosen when subjected to reversing loads. Unimpressive for an "improved" version. This was the Tetrix tweet about the motor:
https://twitter.com/TETRIXrobotics/s...422528/photo/1
"It's official!!! New and improved DC motor released. More power, tougher gear box, increased burnout protection. "
My team made the mistake of upgrading our motors at the start of this season. We still have a stock of used old ones and we are swapping out as needed. Unfortunately it is not FTC legal, but an old gearbox on a new motor might be a good combination.