Klein voiced-over Ziggy Elman's trumpet parts on the soundtrack of the movie The Gene Krupa Story.
In 1953, he appeared on the Capitol Records album Concerto In C Minor For Piano by Dmitri Shostakovich and The Four Temperaments by Paul Hindemith with Victor Aller and Felix Slatkin.
He played piccolo trumpet on Hugo Montenegro's hit version of the main theme to the film The Good, the Bad and the Ugly (1966).
[4] In the 1970's, Klein toured and recorded as a freelance jazz musician, notably in Holland with the Ted Easton Jazzband and American trombone veteran Spiegle Willcox and tenorist Bert Noah.
With Sammy Davis Jr With Junior Mance With Pete Rugolo With the Vince Guaraldi Sextet