Suggestions on Torque box protection?

When I had the bodywork done on my car the body shop made custom rear wheel housings and coated them with roofing tar. The guy said if it holds up for 20 years on a roof it ought to last forever on a car.

 

Dumb Question.

I've always heard that there's no such thing as a stupid question, so here go's. Whats a torque box? And where are they located? I've searched the forum and can't find any pics. Everybody talks about fixing there rusty torque boxes, but nobody shows any pics of there work. Given the amount of rust that I've repaired on my 76, my torque boxes are bound to need some attention.
Thanks.

 

Have a look here: http://mmb.maverick.to/showthread.php?t=26557

 

Thanks

Thanks Dave. That clears up that mystery. Oh and believe it or not mine are in excellent shape. One of the few rust free parts of my car.