My Dad was an engineer, and very clever.
May or may not work for you, but he helped me out.
Use a thin cutter disc, dremel?, and slot the stud for a standard screw driver, short of course. Dad originally slotted my threaded stud with a hacksaw. You can apply reverse force with the screwdriver. Use antiseize.
When you remove the nuts, if you have an air hammer that you can make fit, you can probably spin them off, maybe. Or use the screwdriver and take your time.
You can also use a vice grips with thin jaws, but if you don't cover the threads with tape, and are careful, can mangle the threads.
I wonder if your trunk lid is heavy from Bondo and so the spring steel is having an extra hard time? Replacing the rubber trunk seal also gives a bit of oomph to raise the lid.
New spring steel for heavy lids from Bondo would be welcome. Please let me know if you can sleuth those out.
My 1969, no Bondo, still pops right on up, my 67 which was wacked and has Bondo pops up, not as much, but it works.
Last edited by Dr.G; 07-07-2019 at 07:21 AM.