This photo is from the Southern booklet "Southern Railway System Has the Right Car For Your Frieght" It is from my collection.

No shipment is "too small" or "too big" for Southern Railway's less-carload service in rail-highway containers. If our individual containers in 5 - ft, 10 - ft, and 20 - ft lengths won't do the job. Southern can work out a combination of these - including our standard 40 - ft container - to file the load.

Freight handling can be held to a bare minimum when the 5 - ft and 10 - ft containers are used. Each of these lightweight containers has a pair of slots on the bottom so that fork - lift blades may be inserted. The container may then be lifted off the truck chassis at the loading platform and carried inside a warehouse or storage room for loading. This eliminates the need to carry the freight out to the platform.