Originally Posted by cmac2012

It looks a lot like that only prettier.

I tried using a bit of steel through one of the flange holes and wedged up against part of the casting but the piece bent or popped out. I have a few lengths of some mild steel, 2" x 1/4", I'm thinking to cut about a foot long piece, put two holes in it, and grind away a small arc between the holes to make room for the socket. Then the piece would bear against the floor pan while I break the nut loose with my manly strength. At least that's the plan.

If that doesn't work, I'll try the electric impact. It's not like it's welded on. The Bentley manual says on install to tighten it to 125 ft.lbs., loosen it and then tighten it to 89. Of course, it's been in its current spot for 26 years.