The following quote is from Jose Flores and his book entitled, "El Texto del Nuevo Testamento," published by CLIE in 1977, in which he tells that the translators behind the 1960 Spanish Bible were encouraged to use the CRITICAL TEXTS. I quote from page 322...
"ONE PRINCIPLE ADDED TO THE FIRST LIST OF THE REINA-VALERA 1960 REVISION COMMITTEE WAS THAT WHEREVER THE REINA-VALERA (1909) VERSION HAS DEPARTED FROM THE TEXTUS RECEPTUS TO FOLLOW A BETTER TEXT, WE DID NOT RETURN TO THE RECEPTUS. POINT #12 OF THE WORKING PRINCIPLES STATES: IN CASES WHERE THERE IS A DOUBT OVER THE CORRECT TRANSLATION OF THE ORIGINAL, WE CONSULTED PREFERENTIALLY THE ENGLISH REVISED VERSION OF 1885, THE AMERICAN STANDARD VERSION OF 1901, THE REVISED STANDARD VERSION OF 1946 AND THE INTERNATIONAL CRITICAL COMMENTARY."