According to the option codes it was available
229 Waermedaemm. Glas, Windschutzscheibe Tinted glass, windshield, 230 SL
Actually reading further, code 595 actually says darker on top, and it may have only been available on 250's and 280's, the option codes don't specify, need to investigate further
595 Waermedaemmendes Glas, Front+Seiten, Bandfilter Tinted glass, windshield and doors, darker on top