Look from the underside. There are two brackets that attach to the inner rocker and follow the underside of the floor pan. There are holes that should line up with holes in the floor pan. Since you are going with buckets, there are usually two reinforcing plates that are welded to the floor pan. There should be dimples for those holes and the holes in the reinforcing plates should line up over them. You can see them in this photo I stole off the internet. I circled the brackets. This is a bucket seat car, you can see the inner studs and nuts too.