From http://en.wikipedia.org/wiki/Ken_Curtis: "Curtis was a singer before moving into acting and combined both careers once he entered films, performing with the popular Sons of the Pioneers from 1949 to 1953 as well as singing with the Tommy Dorsey band. Curtis replaced Frank Sinatra as vocalist for the Dorsey band. He was with the Dorsey band in 1941, prior to Sinatra's departure, and may have served simply as insurance against Sinatra's likely defection. Dick Haymes contractually replaced Sinatra, in 1942. Curtis then joined Shep Fields and His New Music, an all-reeds band that dispensed with a brass section.
"Columbia Pictures signed Curtis to a contract in 1945. He starred in a series of musical westerns[4] with The Hoosier Hot Shots, playing singing-cowboy romantic leads. For much of 1948, Curtis was a featured singer and host of the long-running country music radio program WWVA Jamboree."
Curtis also sang in many of the films he made with John Wayne such as Rio Grande, The Quiet Man and The Searchers.
And to hear Festus sing, click HERE!
Just goes to show you cannot judge a book by its cover... 
or a cowboy by his looks!
