I had the same problem and found the answer to getting the bolt out. Lift your passanger side carpet and insulation under the carpet, there is a grill in the floor that you cut out with a pair of tin snips that allows access to the nut on the top...the nut is in a cage and often is rusted and just spins in the cage. I cut off both sides on mine and just installed new grade 8 bolts and nuts. Then just get yourself a small piece of metal and use some 1/8 stainless pop rivits to cover the grill you removed to access the bolt.
