Hey Terry! I think this is the gov't publication you are talking about:

http://www.hnsa.org/doc/pdf/metal-body-repair.pdf


Redlegs, most hot rolled has a mill scale that is a pain to get rid of when prepping for paint. I'd suggest using a cold rolled. It doesn't have the mill scale, normally it has just a bit of an oil film on it from the manufacturer to give it some protection from flash rust during shipping. It's fairly easy to clean off.