I need the groups help again  I'm building one of the above referenced cars and need lettering information as I know very little about the Western Pacific railroad.   

Was the lettering seen on this car in the early 1950's white or silver.?  I have the Champ white lettering and silver lettering set and the white Microscale for the 50' OB cars.  If the lettering was changed by the railroad when did the change occur and what is the best guess for a car painted in the late 1940's likely to be ....white or silver lettering.

Thanking you all in advance

Fenton Wells