Been a having issues getting a stereo installed in my FD.

It came with an old double din alpine unit stuck in the hole but not wired up. Having taken it to a local car stereo specialist they say that the factory brackets are missing which will prevent them from doing a proper install.

I've done some research on the forums but it appears that all the threads I've found talk about a fitting kit rather than the actual bracket it connects to.

Would something like this work or do I need to find a second-hand part?
https://www.carid.com/pioneer/double...0&url=78870747

Currently unsure if my car was originally a Bose unit or standard as heard this can have an impact, anyone know how to tell other than the sub-woofer bein in the back?

Any help would be greatly appreciated!