Torsion bar socket removal

This is a coil over suspension car so I don’t have t-bars any longer. I’d like to cut a 4” half moon shape out of the trans crossmember for my exhaust clearance and then box it back in. My idea was to cut out the t-bar socket first then cap the hole to have a place to tap the hole for the hole saw pilot. My question is has anyone ever had to cut these out for replacement or for some other nefarious reason like I’m doing and how’d you do it? I’m wondering how they’re installed from the factory? Backside is definitely welded in but the front looks too clean to be welded but maybe I’m blind. I’m sure a plasma cutter would make quick work of this but I don’t have one.
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