Basic question regarding tow hitch attachment types, hopefully someone can help out please.

I have a '94 with the 2 tow hitch brackets (same or similar to brackets on the pic of the rusted frame) but mine didn't come with the bolted-on horizontal tube with hitch.

I bought a used factory tow hitch (all one piece welded), very similar to pic of tow hitch. When I went to fit it up, I see the 3 bolt holes for it are in the frame (way forward of the existing brackets), but these existing brackets are in the way.

Does anyone know if the 2 brackets I have now are a) aftermarket, and b) if factory, can they be removed (I see a couple bolts but can't tell if there's welds yet due to major flaking paint - I need to media blast frame and repaint) ?

Thanks in advance.