This model was released in the Series III Nursery Stable Playset #39704. Set included 2 Mares, 2 Foals, and 16 Accessories. The Series III models had a very short sales run as there were production issues with Creata International. These sets have been known to show different molds and colors from the catalog photo, for example, this mare looks grey in the catalog, but I've only seen the dapple chestnut.
This set was considered a Special Run or Collector's Edition, and produced by Creata International for Specialty Market stores (smaller retail stores). Breyer purchased the mold and accessories in 2004.