Re the curved / flat glass in the MW cabs, there were only two variations, and either could be specified. The standard was flat screens, which incidentally are identical to the Scammell cab, along with the aperture and rubbers. These were the normal fitment for export territories presumably because they were cheap to source and easy to replace locally. The curved screens have a different aperture that is welded into a modified cab frame, these screens etc are identical to the Foden S40 cab.