The Rio Grande SP Type Caboose No. 6657 was manufactured in 1957 and 1958. This caboose has an intricate painting sequence with YELLOW painted sides, SILVER painted roof and lower side stripe, and four BLACK painted side stripes with BLACK heat-stamped lettering. In addition, a Denver & Rio Grande Western decal logo adorns each side. This caboose is illuminated and has a clear plastic window insert inside the body. The bar-end trucks are mounted on a chemically blackened chassis with one of these trucks having a tabbed magnetic coupler. Most commonly found with one outward facing brake wheel. There are two variations:
Variation A: Type 1A body die with two ladder slots.
Variation B: Type 3A body die without ladder slots. Uses body mold No. 2357-3 molded in RED plastic. This variation is rare.