Have you tried www.pagauto.com? Have you tried the parts forum? I'd even try eBay.

The thing is that the US trim panels are different. The panels with no front door speakers and pleated seats have perforated leather on the panels. The panels with front door speakers have diagonally pleated leather on the panels. Not to mention matching the color. I don't know about upholstery differences on non-US spec panels.

Maybe you can just swap the full length pocket for the short pocket with speaker cubby.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD