I was fitting the rear floor panels on my 67 convertible. As I was doing that I noticed a small tab of metal (maybe 2"X2") on the front inner wheel well. It was pretty rusted, so I just broke it off figuring I'd fix it later. I looked in the hole with a shop light, and the hole leads right into the frame (adjacent to the rocker). There was what I would describe as sheets of rust in there. I removed most of it, and the frame seems sound, but a little rough on the inside. The outside is smooth and rust free. Is this anything to worry about? The frames obviously had some significant rusting from the inside. Has anyone seen this, or does anyone know how thick the frames were to start? Thanks.