Hi Danny. I'd also like some information about that. I haven't studied it at all, but for the moment I can't see how those plates work?
When I installed my WS19 in my Jeep some years ago. I simply fitted the rubber exhaust cotton reels from a Mini at each corner of a standard WS19 vehicle mounting frame. But I'd love to do it by the book. Please PM me if you acquire info from another source.
Regards Ron