For anyone that's unfamiliar with rear structure and its location (often called "gearbox") there's good clear view in this image.
Right in centre, the interface of (light aluminium colour structure) the PU top support bracket, meeting to its left the carbon fibre based rear structure of the car. Theres regulated 4 or six locators at either end of PU to link front monocoque with rear structure in making one homogeneous "chassis" the car.
Look into the "well" on the aluminium part, you'll see the bolt/fixing the two together. This sited just above exhaust headers as they approach hot side of turbo inlet.
You can see that the carbon rear structure is open (where the exhaust passes in) and in behind that area the clutch and input shaft to the real gearbox is located, and wholly mounted "concentric" within that rear carbon structure.
Just under the mechanic's elbow, you can see a torsion bar (serated/toothed end) that looks to be the anti-roll bar ready to be installed. This lays across centre of vehicle usually to give conflict in chassis roll between the two L&R suspension sets to control that roll in dynamic loading.
A good image with a lot of detail to see for us.