Boomer and Travis aka Lewis and Clarke sang the song in the movie. I was able to find a website for Boomer, who is a "singing cowboy" and still seems to have a career. He is now known as Michael Martin Murphey. Here is his website: http://www.michaelmartinmurphey.com/bio.htm
But what is weird is on his website he doesn't mention anything about this song. Does anyone want to write to him and tell him that this song has a cult following?? It really sticks in your head after you hear it. Kind of drives ya nuts, but it's a cool song. If anyone writes to this guy, please let us know what he says.