The inner fenders are integrated with the “horseshoes” that are welded to the frame box.
The horseshoes are on the outside (tire side) of the inner fender panels.
In my 5357 thread (Search 5357) - the first page, Wade rebuilt the inner structure on my passenger side of the car…… Unfortunately, most of the pictures are gone because of Photobucket hosting issues. Sorry about that, but you should be able to fine pictures of the rear quarter panels pretty easily… someone was selling one recently!
Rocky
Here’s a link to the inner fender for sale.