Taking Fenders off the box

I will work for bananas.

Thank you Everyone for replying to my Question. lots of helpful information. Have been spraying on Deep creep for over a week and they still won't budge. So I have decided on the Nut Spitting idea.
will check out the other possibilities for Carriage Bolt replacements.

If you have compressed air in you shop, you could buy and use a pneumatic small disc cut off wheel. Don't try to undercut the nut. Cut across the bolt and nut. I looked on You tube and I did not find anything I would like to share. Someone suggested using a nut splitter. I do not remember how much space there is so a splitter may not fit.
https://www.kmstools.com/magnum-3-air-c ... ool-172099 This is for the picture, only
Astro Pneumatic is a very good tool and inexpensive. I bought Dynabrade because I like that brand. Dynabrade is 4-5 time more expensive than Astro Pneumatic.