Germain de la Fuente (vocalist from the Chilean group Los Angeles Negros) had an incredible vibrato back in the 70s:
Argentinian vocalist Sandro de America (I remember making a thread for him back in TRP 2.0, and I remember reading a thread for him once in TRP 3.0 which was a lot more detailed than the one I did back in late 2014) was very well known in Latin America in the late 60s, and he had an amazing vibrato way back then, this video is a really good example of his vibrato:
