My long time friend John Cvejanovich just sent me a great book of the 1941 All American Youth Orchestra under Leopold Stokowski. It was found on this great Stokowski fan site in Japan.
Included in the brass section were two young giants of the brass world, John Clyman and Arnold Jacobs:
Back before I began making trumpet mouthpieces I actually played the trumpet and had the honor of studying with John Clyman, who was 1st trumpet with 20th Century Fox studios for 25 years.
You can see scans of the entire 1941 American Youth Orchestra Tour Book here.