What type of diamond plate is this?

[Railroadman]

I'm restoring the utility body on my '66. I'm trying to find the same pattern of steel that was on it but have not been able to find any, and don't even know the proper name for it.

It does not HAVE to be exact original, I can certainly used regular diamond plate and it will be fine, just thought if I had the option of something original-looking, I'd go that way. So what's this stuff called, and does anybody sell it?