On photos, WRX-style instrument cluster plugs look like standard PCB type, only keyed in a non-standard way. If that's true and you don't care for the keys, you may find at least some of them at Digi-Key
. You need to know the pitch (probably 10 pins/inch) and dimensions of the plug.
Used them once w. good results. They sell in any quantity, I needed just one plug and a set of pins (sockets).