Just installed the chest mod. In the close position, the arm is up (12:00) instead of down. Wasn't too much trouble to switch it.
The 4 screws that go into the metal bracket were a bear to get in, especially the left side. I removed some playfield hardware to make room.
Also the tab in the back of the chest bumps into the clear coil cover. I'll probably just dremel that cover a little.
Anyway, this mod is fantastic!