how hard is it to replace driver side and pass. side floor pans on a 78 bronco? can someone tell me the steps to take into this project?

I got the driver's side from Duff about five or six years back. I cut out the rust areas under the pedals with a die grinder, then coated the area with rustmort to stop the cancer. The panel I got didn't have ribbing. I measured where the fuel tank selector and body mount bolts were located and cut them with a plasma cutter. I then painted the old floor with undercoating stuff and laid the new skin in and tack welded it in. The fit was good, and although a body shop may have cut out the entire floor and attached the new panel to the frame, I didn't need it as the body mount area was fine, and fine is good. I know you can order the panels with the ribbing to match the original, but you may not need it. Duff was pretty reasonable, about $35 for the panel, but that was a while back. I don't miss getting soaked when I hit some water, so I would have to say it was a success. Have fun!