If the Mexican time bomb of chaos and revolution ever stops ticking and explodes, it's unlikely that our volatile neighbor will go communist as some apocalyptic right-wing analysts have predicted. This at least is what a crack CIA team concluded after an extensive, in-depth study of Mexico. We have obtained a copy of the resulting report.

One area of special interest to the team was treated in an eight-page Appendix F: ''Communist Presence and Influence in Mexico.'' The task force's conclusion will provide little significant grist for the mills of the Reagan administration's alarmist advocates of a red tide/domino theory for Central America.

''Mexico provides a favorable environment for the Soviet Union and Cuba to push their policy interests against those of the United States, particularly as they pertain to Central America,'' the secret report notes disarmingly. ''The Mexican government allows its territory to be used as a base for political support and propaganda -- much of which is anti-U.S. -- by foreign revolutionaries and communists as long as the government does not perceive those activities as internal interference.''

But the report then adds: ''Because Moscow values its close diplomatic relations with Mexico, the Soviet Union tries to keep a low profile in Mexico, relying to a greater extent on overt activities than does Cuba.''

The report continues: ''Cuba, which has interests of its own in Mexico, has always had a two-track policy toward Mexico -- overt diplomatic and economic relations on the one hand and a variety of open and clandestine contacts with the Mexican left and foreign revolutionaries on the other. Cuba, however, also exercises caution so as not to damage official relations.''

The Kremlin has not been above developing and maintaining ''a wide range of contacts among leftist groups in Mexico,'' the report states, adding:

''The most important is the Unified Socialist Party (PSUM), a coalition formed in 1981 of the Communist Party and several small leftist parties. The Soviets and Cubans have helped fund PSUM -- along with the Mexican government itself, although the latter was under political reform legislation that also brings subsidies to other registered parties.''

The report describes what Moscow hoped to gain from this meddling -- and how these hopes were dashed: ''The Soviets had backed the formation of the PSUM, hoping it would be more supportive of Moscow. The PSUM, however, has differed with the Soviets on such issues as Poland's Solidarity movement and the invasion of Afghanistan, and has been accused by Moscow of being Eurocommunist in orientation and lacking influence in the labor classes.''

Despite the Kremlin's disillusion with its intended puppet party, the PSUM is now, thanks to the Soviets, virtually the only leftist game in town, though its estimated membership of only 30,000 doesn't give it much clout.

While noting that leftist parties ''have been the target of external communist influence,'' the CIA task force observed that ''the Soviets, who have successfully kept a low profile during the last decade, are likely to avoid direct involvement in future subversion.''

As for Cuba, the task force concluded that Fidel Castro will refrain from subversive actions in Mexico as long as he views the Mexican government as generally supportive of his policies. This restraint could disappear, however, if Castro doesn't get continued support -- or if Mexico's internal situation should deteriorate.

In summary, the CIA task force concluded: ''Although the communist countries, particularly Cuba, have developed a wide range of contacts and influence mechanisms in Mexico that could be used to weaken the Mexican government, we believe the government retains the power to forestall such an effort.''