Thanks, that's what we were thinking too. I thought maybe someone on here would have experienced this before and would have a solution. Appreciate your time.

I'll post pictures when we figure it out.

In the meantime, anyone else feel free to chime in, we'd appreciate it.

 

can u use the drain hole to gain access with a flexible box end wrench?

 

I just ran into this on my son's car as well. Don't cut the frame to get to the nut. The best way is to peel up the carpet and go through the floor so as to not interfer with the strutural integrity of the frame.

I simply took a thin bladed grinder and made a couple of passes at 90 degrees to one another so I could "peel" the floor back, carefully heat the nut up with a torch and then it should loosen up for you. May need someone up top to hold the nut and someone down below to run the wrench or impact. If that doesn't work you can cut the head off the bolt, grind the retaining rails away from the nut and then drive the bolt out from the bottom.

Get a new bolt and nut, tighten it all back up, tack weld up the floor and get some high quality autobody seam sealer to apply from the top and some good quality undercoating to spray from the drain holes in the frame below and you should be good to go.