Driveshaft Safety Loop Requirements?

[DETON8R]

Does anybody have the requirements for driveshaft safety loops? I realize that you can make them out of anything, however I'd like to know the rules from NHRA or any other sanctioning body. I'm planning to use flat stock, as I can bend that as I need into shape.

Size of flat metal stock? Width and thickness?

Or if tube stock is used, OD and wall thickness?

And is there a requirement for front loops vs. rear loops?

And mounting requirements? To body sheet metal vs. frame mount?

Thanks Everybody!!