Check these pictures out. I'm sure I could knock these out with an air chisel but I'm not sure that's the best way, I'd sure hate to destroy the floor or inner rocker panels.
What's the best bet to get these out? Also, the bolts, how would I remove these? I'd guess they're rusted on good and the broken off mount parts would spin if I hit them with an impact. Maybe I could hold them from rotating with a vice grips? Check out the pics: