I need to remove a partially rusted seat rail beneath the passenger seat on the right. I read on a post that these could be spot welded in and I could drill out the welds and remove the rail. On my car it looks like it's part of the pan and I don't see spot welds. Any ideas on how to remove? Maybe I could get a chisel underneath and pry it up. Or cut and then grind down what remains.

I used an air chisel to remove mine, and they were spot welded. Keep in mind I built my own seat rails to replace them.

The rails are spot welded in and if you clean it up enough you will be able to see them. When I removed my bad floor pan I drilled mine out and then made piece to repair what was bad. You can buy seat rails if it is more work than you want or can do. I have a lot of equipment to it is no big deal for me.

Air chisel? Sounds like it's time for a new tool! At Cdn Tire in Canada the tools sometimes go on sale really cheap (eg. 70% off). No idea why but you can sometimes get a $100+ tool for $29!

Harbor freight for 16 bucks. Get a chisel kit with it. Just grind the v-groove chisel flat.