where does this floor brace go E-body

Putting a parts list of body panels to replace when I come across something called a floor brace panel rear seat rocker wheelhouse - Its supposed to go between the seat pan and the inner wheelhouse and rocker panel - I am gonna replace my rear quarter panels - I haven't seen behind them in almost 20 years but I don't remember every seeing any sheet metal that looks like that. I guess I could wait to order stuff when I pull off the quarters. Thanks
-Steve

i haven't seen the list of sheetmetal to order for E bodies.
i know there is a thick brace thats under the rocker panel and on top of the inner rocker panel. it starts at about where the 1/4 panel jamb starts and runs to the rear wheelhouse. it's about 2' long and helps reinforce the torque box area. the rear window guide bolts to a bracket on this part. on convertibles this brace runs the length of the rocker panel.
is this the part you are describing?

Are you talking about the panel that goes between the trunk pan and rear quarter panel like this?

I believe it is called the drop-off panel.

I think the OP is referring to this, but I'm not 100% sure

https://www.c2cfabrication.com/prod...loor-brace-side-support-for-rear-seat-rh

that's the one, where the heck does that go, I don't seem to remember that last time I did major bodywork on this car, its been >20 years and these repro parts weren't as easily available then
- Steve

Those are the trunk extensions.

my guess is undr the rear package sgelf and the X brace between the side attach to it.

That may be the brace that attaches to the frame rail under the car. I think it connects to the rocker end and wheel tub as well. Im not positive but I think thats it.