Originally Posted by 98camarod
It looks as if they brazed the quarter to the rocker. Isn't it supposed to be separate and the quarter is spot welded to the top of the rocker?
Indeed it is. Consider the braze as filler material that will grind right off. The quarter may have been replaced before and not welded there. Reason I said something about the pillar brace is that same guy might have whacked the rusty bottom off it. Heres a glance at a 69 Camaro in that spot, that I think I have secured in a decent way in the bottom pic. Ignore my tab on the right, but to the left you'll see where the brace was patched and the new quarter is sandwiched between it and the rocker.
Once you grind away the braze, you can pull the old flange off. At least it looks like in your pics that theres a layer over the rocker, stuck with braze. Get rid of that and go down to bare rocker. Maybe theres a Chevelle guy around with specifics on that body.