Is the XJ Saginaw steering box Cast Steel?
 

As it says, is the XJ Saginaw steering box Cast Steel or Cast Iron?

I need to add some ports to the box for my hydro assist and (provided it's steel) would rather weld fittings rather than tap (I'm going to strip the box down bare and rebuild either way). If it's cast steel, I should be able to pre-heat to 500 degrees and TIG with some stainless rod.