This is the UPPER and then the panel under your  bum in the back seat area.

This is ONLY to help show the difference in the harder to verbally describe area.. UNDER the rear seat and partially again up the back a bit.. of the 70-81 era  Firebird & Camaro.

Showing where they join so you can order the right part if needed.

Using this panel.its possible you may need to move the two outer seat belt anchor points slightly .. depending on the year and the conversion/ seat belts used.