S1 - fixed, one piece, plexiglass, side windows
S1A & S1B - fixed, plexiglass, quarter lights with pop-out plexiglass, side window (also known as "fall-out")
S2, TC, Special - fixed glass quarter lights with electric, glass side windows (do not go all the way down, almost perfect laminar flow results in no air intake at speed)
47 - front hinged, rear opening, one-piece, plexiglass, side windows (at speed, these can suck engine fumes into the cab)