I heard the three guys would cruise around listening to a particular radio station. The station was close to if not on the other side of the border in Mexico. The station call letters had an X in them and was known as "The X". The "Little ole band from Texas"were very fond of X and as I recall the X had a way moving around so as to escape the FCC. Pursued because of the content which could be called questionable by the conservative faction in south Texas prevalent at the time I'm sure the guys took some of the things they heard and incorporated it into their own. Sound.