The group's four-part harmony set within the traditional Mexican trio style "plus one" that echoed the
Mariachi sound developed a newness in music that set the group apart from their modern counterparts. The unusual blend of Jorge's tenor with Gualberto's tenor – countertenor voices blended with the deeper voices of Arturo and Javier voices played in
Bossa nova,
Samba and
Jazz styles, were the reason the group was continually contracted in many Lounges throughout the United States. In the mid-1960 the group was booked into night clubs and lounges in
Las Vegas,
Nevada. They performed with
Paul Anka,
Judy Garland, and many entertainers including featured in the French production show
Casino de Paris at the
Dunes, Las Vegas, produced by
Frederick Apcar. The group also appeared in Cuba, Spain, Puerto Rico, Central America, Argentina. Los Hermanos Castro sang on television shows such as
The Judy Garland Show. Many of the songs the group performed were written by Arturo. Their single "Un Hombre y Una Mujer" reached the number three position on the Puerto Rico singles chart in June 1967. In 1971 they were Brazilian Festival winners. ==Group reorganizes==