Muchachos...they were great. Didn't they get disqualified for marching over-age members in 75, or 76? They never recover after that. Too bad.
Yes, in '76. They had (I think) 8 people who were over age, including 2 of their premier soloists. They had a hell of a repetoire.
Oh! Check out http://www.cabs.org/repertoire.asp
I think they have some of the original recordings of '75 Muchachos on their audio page.