On the Spiderfield layout there are two Bay Window Cabooses, one Cotton Belt and one Southern Pacific.
In 1968, Southern Pacific subsidiary Cotton Belt (officially the St. Louis Southwestern Railway) received 20 cabooses from International Car Company. These were the first SP cabooses to use 50 ton trucks, starting the C-50 series of cabooses.
In 1970, 1972, and 1974 SP returned to International Car for 181 cabooses, plus 16 for Cotton Belt in three groups. For the next four years, SP did not acquire any new cabooses. Instead, 207 older cabooses were rebuilt by the Sacramento Shops. In 1978, SP, again, bought cabooses.
By then, International Car was a division of PACCAR (formerly Pacific Car & Foundry). The 50 cars of the C-50-7 class were built at the same Kenton, Ohio plant as the previous C-50 series cars. In design, they were similar to the previous C-50 cars with only a few changes.
Their paint differed by having the roof painted the car body color and the road name was moved to the right of the bay window, and they featured an axle-end generator connection. They were also the first new cars in the 4000 series. In 1979, 50 cars of the C-50-8 class were delivered, with some minor detail differences when compared to the earlier C-50-7 cars.
In 1980, the C-50-9 class of 75 cars was delivered. The C-50-9 class was unique in that they were delivered without any windows in the car sides, in order to increase crew safety and reduce repair costs. They were also the last group of new cabooses delivered to SP.