That seat looks like the 2002 factory option seat. Scheel model 201. I have the same seats in my 02 and love them. My seats have the same recline adjustment hardware/hinge to connect seat back and base. The Scheel model 500 looks similar until you see them side by side. Yes, they have different pleat pattern on the seats (aka "foam stitching"), but they area also a bit larger overall.... most noticeable at the leg bolster area where it extends out a bit more. The Scheel model 500 feels a bit large in the 02 cabin, whereas the model 200 fits very well.
It looks like you've got a Scheel slider attached to the bottom. Sorry I can't be of help identifying that base plate. I removed the height adjustable Scheel sliders and used Recaro adapters to mount them to the 02 sliders.