The Fisher Body 1969 Service Manual on page 15-50 shows a picture of the back seat and tabs (view B) The part on the last post where I got the measurement with the steel rule and the yellow paint circle, that is called floor pan bracket and it bolts the seat down. You'll see in the pictures I only have one tab in the wheel house area. Before I got the car they did some work and now it's missing. I don't think you need those tabs. They're pretty flexible and it feels like if you bent it back and forth a half dozen times it would break.