Pesky front bumper bracket anchor nuts

[hemi68charger]

Hey gang.. I'm know the experience of a anchor nut ( don't know the technical term ) breaking its weld within the framerail has happened to others.. Are there any experiences on a fix that can be shared... My buddy and I were disassembling his recently acquired 1970 Challenger T/A project and two of the dang bumper bolt anchor nuts just spin, the weld has been broken that holds them in place.. Can't get anything in the holes on the framerail to wedge to prevent the nut from spinning.. Any suggestions prior to the, what seems inevitable, cutting away at the framerail in order to access the anchor nut...

Oh the joys of a 40+ year old car.......

Troy