Ten years after the fall of Saigon and after the trauma of their return home, most Vietnam veterans have successfully entered the mainstream of American life, according to a special Washington Post-ABC News survey.

When they entered military service in the 1960s and early 1970s, three-quarters of them had no education past high school; a fifth were dropouts. But more than half went back to school later on. And today, the survey shows, a Vietnam veteran is more likely to have gone to college than a man of his age who was not in the service.

With education have come job prospects and incomes similar to those of other men the same age, according to the survey. The unemployment rate for the Vietnam veterans surveyed is about 7 percent, also similar to that of all working-age Americans. Three of every four of the Vietnam veterans surveyed said their annual household incomes exceed $20,000; almost half take in $30,000 or more each year.

Most also are now married and have children and homes of their own. Eight of every 10 Vietnam veterans surveyed are married. Ninety percent of them have children and 43 percent have three children or more.

Strikingly, 78 percent of the Vietnam veterans surveyed are homeowners, the great majority paying mortgages on traditional, single-family houses. More than other Americans, they tend to live in small towns and rural areas.

Thus, despite the grief and anger many of them experienced during the war, followed by bitterness when they first returned home, Vietnam veterans appear statistically, and perhaps unexpectedly, to have settled down to lives not unlike those of the veterans of World War II.

One of the most interesting findings in the survey was this: Asked whether they personally benefited or were set back in the long run by having gone to Vietnam, 56 percent said they benefited; 29 percent said they were set back. There are qualifications to those answers.

"Since I survived, I feel I benefited," a former Army corporal. "I learned a lot about the psychology of people under stress . . . . But it took the two best years, from age 19 to 21, out of my life."

Said another: "As far as growing up, maturing, I benefited. But that's the extent of it."

One particular group of Vietnam veterans, however, has adjusted less well. Although they are a minority of all who served, they are the ones Americans think of most when remembering the war: those who survived heavy combat. They tend to be slightly less well off than other Vietnam veterans, somewhat more bitter, and suffering from more bad memories and personal problems.

These conclusions are drawn from a survey of 811 veterans who served in Vietnam and Southeast Asia, selected at random and interviewed by telephone last month in the Post-ABC News survey. An additional 438 Vietnam war-era veterans who served elsewhere also were interviewed, but the findings in this story are based almost entirely on the responses of those who were in Southeast Asia.

Those surveyed are sharply divided about whether the United States should have sent troops to Vietnam. But generally they said they are proud about having served there nevertheless. Unlike the responses of most Americans interviewed in other national surveys, a majority of the Vietnam veterans think that they have a clear idea of what the war was about and that the United States could have won, if not for the politicians.

"If the politicians would have let the military fight it like they know how, I think the outcome would have been different," said Philip Anton, 36, of Pekin, Ill., who was a radio operator for a U.S. Army artillery unit in Vietnam for 11 months in 1969 and 1970.

"The war could have been won in a month's time," said a former rifleman, Sgt. 1st Class Alfred Simmons, 39, who is still in the Army, now stationed in Virginia. "We let a Third World country defeat us and make fools out of us . . . . The government should have let the military be in charge."

Scores of the Vietnam veterans surveyed volunteered similar comments. A majority said William C. Westmoreland was the commanding general when they were in Vietnam, and two out of every three who have feelings about Westmoreland said they approved of him as a leader.

The Post-ABC poll and similar studies underscore differences between veterans of heavy combat and the others. About 30 percent of those interviewed in the survey said they were in heavy combat.

Item: Of the veterans in the survey who did not see heavy combat, 29 percent saw their first marriages break up. Of those who said they were in heavy combat, 41 percent saw first marriages break up. In both groups, most remarried and are married today.

Item: In the Post-ABC survey, veterans were asked about eight types of problems they may have had on release from the service, including health, money and job problems, loneliness, drinking, use of marijuana or other drugs, difficulty in getting along with family and friends, and emotional strain.

Half of those who said they were in heavy combat reported suffering from at least three of the afflictions listed. Fifty-three percent reported undergoing emotional strain, 44 percent said they had a drinking problem when they came home, 42 percent cited bouts of loneliness, 40 percent said they did not have enough money to live on, 33 percent had difficulties with family and friends. Use of marijuana or other drugs was mentioned by 16 percent.

Among veterans who did not see heavy combat, fewer than three in 10 said they suffered from three or more of those problems after coming home.

Three of every four veterans of heavy combat said they agreed with the statement that "I often find myself still thinking of the death and dying" during the war. Among the other Vietnam veterans interviewed, 48 percent said this statement applied to them.

One widespread belief about the Vietnam war is that black Americans were called on in greater proportions than whites to serve. The U.S. government has insisted that is not the case. Only 8 percent of those interviewed in the random Post-ABC News survey were black, a figure slightly lower than the government's own numbers.

But the survey also suggests that blacks did more than their share of the fighting. Almost half the blacks, 30 of the 67 interviewed, fell into the heavy-combat category, while three of every 10 white veterans interviewed said they were in heavy combat.

Possibly for that reason, more black veterans than white veterans said they encountered problems on their return to civilian life.

William Evans, like 43 percent of all veterans interviewed and 51 percent of those who saw heavy combat, said that being in the Vietnam war was the biggest event in his life. It may still be.

Most veterans, 68 percent in the survey, do not belong to any veterans' organization. Only 16 percent said they were members of the Veterans of Foreign Wars, 12 percent the American Legion, 2 percent the Vietnam Veterans of America.

Evans is active in the Vietnam Veterans of America in the Medford, Ore., area, where, he says, there is an extremely high concentration of veterans. "Our group is doing a lot. We have counseling not only for Vietnam vets but for their wives and children and families. We go to schools and talk to the kids and tell them what really happened: that there was no 'God on our side.' "

Of himself, Evans says, "It wasn't until I went into counseling with a Vietnam vet . . . that I started to have trust and be helped . . . . He knew what it was all about: when to ride me hard and when to ease off. In a year he had helped me a lot. I'm continuing some therapy and I'm counseling other vets. My healing is continuing through helping the others."

About half of all Vietnam veterans think that one result of the war has been to prevent the nation from becoming involved in subsequent major conflicts. But three in 10 think that Central America will be the next Vietnam.

"I think the rehabilitation of the Vietnam vets that has been going on now is a concerted effort to make the whole thing more palatable and honorable to the American public, sell them on the idea of sending the military off to fight in Central America," said a Naval Academy graduate, Jack Moynehan, 41, of Newport, R.I., who as a lieutenant was commanding officer at Sa Huynh, a small combat support base 100 miles from Da Nang.

"It was almost better when they called us baby killers," Moynehan said, "because then the public wouldn't want the military to do that sort of stuff again."

But most of the veterans don't share his view; 70 percent are not fearful that Central America will become "another Vietnam."