If the identification is confirmed, Mr. Camarena Salazar, who was 37 years old, would be the first American drug agent slain in Mexico since the United States and Mexico began their joint antinarcotics efforts in the early 1970's. United States officials have declined to specify what he was investigating at the time of his kidnapping.

The ranch where the bodies were found was the same one where Mexican investigators said they engaged in a shoot-out last Saturday with people they suspected were drug traffickers.

The police arrived at the ranch, 70 miles from Guadalajara, on Saturday to investigate a tip that the two missing men might be found there, according to the Mexican Attorney General's office. The police said that they were met by gunfire as they approached the main house and that in the ensuing battle one Mexican agent and five residents of the ranch - a former local legislator, Manuel Bravo Cervantes, his wife and three sons - were killed.

The two bodies found today were described by a spokesman for the Mexican Attorney General as ''truly unrecognizable.'' They were taken this afternoon to a hospital in Guadalajara, where where tests will be conducted.

The Government press agency Notimex quoted local officials in Zamora in Michoacan State, where the bodies were first taken, as having said that both showed signs of beatings and that one had a fractured skull. They said the two men appeared to have been dead about three weeks. The Attorney General's spokesman, Francisco Fonseca, said one body was dressed in gray pants and a yellow shirt and the other was nude.