I had a quarter size rust hole at the bottom of my wagon tank.
Pulling it meant pulling the axle, couldn't buy new or fill it with water, as far as quick fixes and patches nothing worked.
Recently bought a tanksinc efi tank for something else, came with a block off plate for the sending unit.
Hmmm. Back to summit, bought the threaded retaining ring, a new rubber gasket (forget the material but made for gas), and the screws with o-rings.
All tanksinc stuff.
Retaining ring is a C shape to slip inside, widened and rounded existing hole, drilled holes for screws, actually ran a hose on the bottom while drilling because I'm paranoid.
I had to bend the block off plate a bit on one side to match contours of tank.
Hasn't leaked a drop in years, not a weep or anything.