The QH registry started out in 1940. At the time, “grade” mares (usually Arabian, morgan or Tb) could be entered into the books… they didn’t get a #, but the foals did. It was a little harder to get a stallion into the books, but not impossible. In the 1960s (late-ish) they cracked down a bit more on that.
Three Bars (1940-1968), his stud fee in 1966 was $10,000.00. There are some standing for more now, but with inflation, I’d say it’s probably still one of the highest stud fees for a “QH” stallion
Shining Spark for instance, stood at that fee until 08. Hollywood Dunit was right around their too, and this is 40 years later!!