he Southern Railway's use of steel bay window cabooses dates back to the later World War II period, when freight traffic demands proved too much for the railroad's aging wooden caboose fleet. Although Southern rostered several series of subsequent steel cabooses with high-rise cupolas, the steel bay window design would come to dominate the rosters all the way into the 1980s. Southern's bay window fleet fell into two large categories. The first includes older bay windows built in the 1940s and 50s and then rebuilt in subsequent eras, sometimes twice, by the railroad itself at its Haynes Shops. The second includes bay windows built in the 1969 to 1974 period by outside builders such as Gantt Manufacturing of Greenville, South Carolina. Combined, the Southern bay window fleet proved to be a recognizable and unique design in American mainline railroading.

Different number series featured slightly different details, including roof lines, trucks, window size and placement, and overall length ... but a basic design pattern remained consistent: a low-slung boxy carbody making use of side bay windows instead of tall cupolas for observation. Standard features included porthole windows on the ends, square aluminum-framed windows in the sides, cantilevered hand brake mounts, drop down steps mounted under the frame, and padded bi-directional seating inside the bay windows. Most cars included axle-mounted generators for producing electricity for crew lights and radios. Some models utilized roof-mounted solar panels to power rear-end lighting. For a period in the 1960s, the railroad painted its bay windows in a darker railroad brown; however, later the entire fleet would become known for its bright red paint tone. Cabooses assigned to local freight service were usually identifiable by bay window sections painted in yellow. Road service cars carried all-red bodies. The rebuilding programs of the early 1970s prompted a renumbering scheme, after which all but five cars received 3-digit numbers preceded by Southern's much utilized "X" — indicating service and work cars.

Complete bay window rosters are difficult to find, but our research indicates that Southern's bay windows fell into the following numbering series and assignments:

Most groups remained in service on the Southern up to (and some through) the Norfolk Southern merger in 1982, which took place in the same period when state and federal laws relaxed and mainline railroads were beginning to abandon the use of cabooses on freight trains. By our count, at least 150 bay windows survive today. A precious few can be found around the Norfolk Southern system, on display on railroad property. Many have been preserved at railroad museums around the southeast. Many more were donated or sold to local municipalities and organizations, and can still be found today on outdoor display in various states of repair. The bulk of these sites are in Alabama, Georgia, Tennessee, and the Carolinas. A few cars have still enjoy active use in the employment of tourist railroads or freight shortlines.