This Southern Pacific set is one of the earliest plastic sets. The four wheel plastic cars were not lettered. Instead, the set was sold with a decal set which could be applied to the cars. Fortunately for me, the youngster who owned this set wanted to get his money's worth so he applied all the decals! He produced a Bessemer and Lake Erie & Pennsylvania gondola and a New York Central & Baltimore and Ohio boxcar.
Many collectors might be annoyed at this departure from prototypical appearance but for me it shows that the set was offered with optional decals.
Below is a picture of the box showing the number. There was a B&O set offered in the same box with the same number but it has a 45 watt while this set has a 50 watt transformer.