Bay with black points and a solid face. This model tends to be a medium/dark bay with no nose shading as compared with the #1017 Topside and Stevie set. Available as a single model #9010 from 1984-1988, in Bay, Chestnut and Black.
The Bitsy Breyer Jockey Set #1010 included Bitsy Breyer doll, Racing Tack, helmet and comb from 1984-1987, in Bay, Chestnut and Black.
Available through Sears in 1984 as #49N21057 and included a Bay Clydesdale, Bay Arabian, Bay Thoroughbred, Black Morgan and Unicorn.
In 1986, it was pictured in the 1986 JC Penney catalog, that the Chestnut, Black and Bay Thoroughbreds were available in a set #671-2483. However, the description mentions the set includes an Arabian Stallion, Palomino, and Bay Thoroughbred. Hopefully, I can find photos of what this set actually contained.