So far 2 of 3 attempted are spinning but not coming out. Assumption: Stripped. What are my options as far as getting them out? Keep in mind, this car is sitting on jack stands fully extended. Cannot go any higher. Gut instinct says I'm cutting them out....am I right?

The J-nut rusted through, it's really common. I cut the heads off with a cutoff wheel and then fished the rest of the bolt and J-nut out through the holes in the frame. Some guys use a grinder to do the same, and some guys cut holes in the floors to get at the back.

That's what I figured, but not what I was hoping to hear. Oh well, try again tomorrow.
Thanks!