Thanks. The surrounding area seems rather solid, but it's hard to tell. I bought the car about 6 months ago. I climbed under it, but only on the drivers side, so I didn't even see this.Oh wow, yeah that's not good and it will only get worse if you do nothing. I'd get that looked at by a professional and discuss options. If the surrounding area is actually solid (when the rust through is that bad it usually isn't), they might be able to weld in a patch plate, or you can DIY if you're good with a welder.