Panel thickness Q

[Ochre]

Got a quick question about the 69-72 blazer's....I've got a '71 K5, and need to repair/fabricate a few parts on the body (Okay, a lot of parts on the body, but anyway...)

I'm looking at repair panels, a few brag about being 19 Ga steel or somewhere around there - what I'm wondering is, what is the thickness of the stock panels? I was thinking about buying some steel sheet off of ebay or a local surplus shop, to patch the flat areas under the rear bed floor and behind the front seats. So how thick are the stock panels?

Also, does anyone have a link or chart of what gauge corresponds to a metric or fractional measurement of thickness? Thanks.