Yes, a small nut "cracker" might work but most don't have them or want to buy a tool only use once. Many stores only have larger versions to handle nuts ~ 1/2" & bigger threads.
If have a "dremel" can cut the front nuts w/ thin cut wheel this way...
Cut more then once if needed, avoiding the bolt thread.
Many have very thin cut wheels that came in a tool kit but also make "heavy duty" that's a bit thicker could work too. Reinforce wheels are too thick for small nuts to control the cut.
Even if have left nut threads in place, screw driver etc can break it or threads don't have strength left to hold tight turning now.
Back nuts often don't rust unless sunroof leaking etc.
Front nuts & track rust because of crap on your feet like road salt in winter.
W/o pulling the seat, maybe get lucky just oil the track but Fiero is so low very hard to do that w/o making a huge mess.
