I can't say for sure about the chrome, but in general Chrome was not meant to be show especially for trucks in those days. The lenses were glass originally in 1937 for Oldsmobile and 1939 for Chevrolet cars. They were re-introduced in 1948/9 for the Suburbans, Panels and Canopy Express as signal lights The 1949/52 Chevrolet station wagons also got them as signal lights. I am not sure what the year change is, but I think it was around 1952 or 53 when they switched to plastic. The panel barn door light and the CE/Suburban light also were changed to plastic.
