There was never a module version of the WK4 or WK8. Generalmusic looked at the possibility for some time but there was no easy way to incorporate the large screen comfortably so it never even got to the prototype stage.

In chronolgocial order, there was a WS-2 module (1991), a WX-2 module (1994) and currently the WK-2 and WK-2 Oriental module.