Before I feel comfortable installing the new inner rocker, I needed to replace the patch the previous person had welded into the right rear inner wheel well that has started to rust out. I bought a new inner wheel well panel from NPD and cut a patch to fit the area that I wanted to replace. Here's what it looked like before I started cutting.
I ground around the area I wanted to replace; above the rust; and then marked and cut out along a straight line up to the seam of the outer wheel well panel. Note the rusted flange where the inner wheel well attaches to the floor panels. One challenge will be to patch the flange.
Finally, I cut out a patch from the inner wheel well panel and test fitted it into position. This is one of the Taiwanese parts (Dynacorn?) and it fits very well.
Because the area around the wheel well at the rear floor was rusted away, including the flange to which the wheel well was welded, I had to fabricate a patch out of 20 gauge sheet metal and weld it into place.
This is the new flange. Yeah, it's a bit ugly but it's the most complex patch I've had to make yet since it curves along the rear frame rail, wraps around the wheel well, and has a flange 90 degrees to all that curving.
I prepped the wheel well patch for welding by drilling it with holes where I intend to make the plug welds and then coated the areas that would be between seems with a weld-through primer.
I welded, and ground the welds this is the completed patch area. You shouldn't be able to tell the patch is there after it's painted. The camera does weird things with reflections but the metal is pretty smooth.
From the inside where the new floor patch meets the new wheel well patch.
Here's a picture of the same area before the patch work.