My driver side rocker panel is badly dented. Looks like the car was driven over a tree stump. How hard is it to replace the rocker panel. I think the damage is too much to fix. I need to replace the dog leg..

Try Tabco, some grinding and welding.

MRK3COBRA

This is what it looks like when you take them off. Mine were cancered pretty badly so they had to come off for complete restoration. Also do a general search for ROCKER PANEL REPLACEMENT on this site. There are some good photos of what the replacement part looks like as well as installation. It can be done with the right tools and patience. Don't weld it until it fits perfectly. If you have to a professional can fit them for you.

Sorry to be a downer, but if your asking about replacing the rocker and dogleg it might be too much for you to attempt. Better to have a body shop do the work if you car about the car.