Guillermo Díaz had the following finishes at major championships – 1983 Pan-American Games: 100.0 kg. Greco-Roman (3rd); 1991 Pan-American Games: 130.0 kg. Freestyle (5th); 1991 Pan-American Games: Unlimited Freestyle (5th); 1995 Pan-American Games: 130.0 kg. Freestyle (6th); 1995 Pan-American Games: 130.0 kg. Greco-Roman (8th); 1984 Central American Championship: 100.0 kg. Greco-Roman (2nd); 1990 Central American Championship: 130.0 kg. Greco-Roman (2nd); 1990 Central American Championship: 130.0 kg. Freestyle (3rd).