It's all about racing
The bumpers were made from Ford "torque tubes" they weren't just for looks. We jack up the car under the bumpers because the body is so close to the ground.
The all aluminum body shape was formed around the inner framework. After the war there were a number of very talented metal shapers in Southern California. I believe this image was found on the internet.
Another image from the internet.
This is another shot from the web. My friend Tony Adriaensens has written a great book on the subject called "Weekend Heroes", I believe this is one of the images from his website. Watch for the upcoming second edition. Thanks Tony.