The Outer Rocker Panels go inside of the the "Dog Legs" at the bottom of the Door Hinge and Quarter Panel Pillars. Are you sure it's the rocker that is rusted in that area or the sheet metal on top.
In any case the one's I mentioned before are Reproductions and when test fitting mine it seemed long enough to go where the old one was but I only wanted to replace part of the rocker so I didn't mess with the ends.
It's not a technical name but used often to refer to the area located at the bottom of the pillars where it meets the Sill panel and Outer Rocker. I guess they call it that from the shape of the curve.
Your only source for one of those is from another car. It's actually part of the body and not a body panel or skin.
Still need the passenger rocker? I just cut the inner and outer rocker off an 87 limited from Texas. I can send pics if you are interested. Let me know.
Mike. mandslac@earthlink.net