Does anyone know of an aftermarket place you can buy something like the metal rocker panel reinforcement (which the rocker panel bolts onto?)
I have a Limited 93, and my rocker panel is the lower lip that runs across the bottoms below the driver's side doors. It bolts onto something under the car, which is what i am looking for. Mitchells calls it a rocker panel reinforcement. All of the online places for GM parts do not have this panel.
You can see all the rust on the ground under the car...that *was* most of that panel.
http://amopower.com/files/Buick/DSC00453-1.jpg

Underside of the rocker panel. That one inch gap or so was actually all metal. Now it is all crunched away in the rustpile.
http://amopower.com/files/Buick/DSC00452-1.jpg

Have you checked for any LeSabres at junkyards? I've been under several of these cars back when I was looking for an ELC level sensor, and even down here in S. TX I've never seen a junked car with that much rust underneath.

No. I'm not even sure if those panels are welded on or screwed on, and I think it would be a heck of an effort pulling one off a junker. I'd rather buy new and rustproof it befire I even put it on, but I dont know if these can be bought. Also afraid to take mine off and find that it wont go back on again due to everything being so rusty. I'm sure most of the bolts holding the outer panel on are glued on with rust.

This does not bolt on, this is a welded inner panel, usually not available AM.