Tub time. The flange of the tub is sandwiched between two layers at the top. Getting the old metal out from in between was a challenge. The huge holes on the outermost flange were two-fold. 1) because it was so hard to separate, it required a larger drill size. 2) My game plan was to plug weld to the inside flange first (through the larger hole). Then finish welding the outer flange.
Mock up with tub
Drill, drill drill, drill
And getting welded... You can see I took the opportunity of no quarter to work on the trunk floor.. lots of old drilled holes (battery in trunk ?) and lots of hammer and dolly work. While things were opened up I was stripping the "to be painted" surfaces to bare metal and the "no show" surfaces were getting wire wheeled sanded and either Por-15 if surface rusted or DP90 if bare and clean.