1987 front stab bar removal
 

I have new lower control arms to install on my daughters Camry. Well, made some exploratory loosening of the related nuts etc. The "welded" and hidden nuts on the drivers side sway bar bracket have broken loose and now spinning. The piece they are inside of is removable but I am afraid of running into the same issue with 30 year old bolts. Also, anyone have experience replacing the lower control arms? The ones I have, have all the bushings etc already installed so it's just a matter of removal and reinstall. TIA