Dale,
Try looking in "The U.S. Army in the West, 1870 - 1880", page 72. It appears that many cavalry in the southwest wore their stable overalls.
Also try looking in "The Horse Soldier 1776 - 1943" Volume II, by Randy Steffen. He is supposedly the expert on cavalry of the U. S.
Hope this helps.
Bob (Cactus Rope)