In this shot you can see the cowl supports going up behind the dash. The cowl supports will take the load of the stressed tunnel and feed them into the foot boxes.
Also, you very clearly see the door hinge pillars in this photo. The plates the door hinges pillars mount to are hidden under the doors. That is one of the big secrets for the incredible stiffness of the chassis.
The rear bulkhead is also very clear in this photo. The rear bulkhead forms the back of the cockpit and takes all the loads from the wheels and the differential and feeds them into the tunnel and down along the sides of the chassis under the door sills.
