Each repair of that kind is different. Have several experienced body shops give you an estimate.
It really depends on how far gone they are. I assume you have rust issues (these rust underneath the plastic molding affixed to the rocker). I would strongly recommend that any work done be done by a professional body man and there are panels available to make this repair: http://www.tri-proautomotive.com/servlet/the-Ford-cln-Taurus/Categories
They are called rocker panels.
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rocker panels
Depending on the amount of rust you can bondo the holes. You will ned to cut the rusted parts. If the area is large then fiberglass will make a better and more durable repair than bondo.
Fixing the rocker panels on a 1995 Chevy Corsica will not compromise the frame. Fixing this will help the vehicle last longer as far as rust goes.
Rocker panels are located on the sides of a vehicle, situated between the front and rear wheel wells, just below the doors. They are part of the vehicle's structure and provide support to the body while also serving as a protective barrier against road debris and corrosion. In some vehicles, rocker panels can also serve as a mounting point for side skirts or running boards.
Any good auto parts supply store. Speedgrip adhesive is the best.
No one makes panels for the 1st gen. You'll have to buy the F150 super crew rockers and trim the length off the back.
The Rocker grossed $8,767,338 worldwide.
Find replacement rocker panels, specifically for a 97-03 Grand Prix, cut-out the old and weld on the new, then paint and u should be good to go........keep in mind that i would be alot less expensie if you order the replacements online Good Luck !
The rocker arms are not torqued to a specific setting. Follow the instructions in any repair manual for the proper method for adjusting backlash.