I have always believed that they never made a pump plate in that size.With that in mind,one of PCM's older books does list a die cut shield shaped truck sign at 12".They don't list the other dimension.It just might be a real truck sign.

BTW, the pop in Vic's catalog is listed at 12" X 12".I don't collect much Phillips stuff so it will be interesting to see what some of the other guys think.